101 Best Physics Projects for Students: From Beginner to Advanced

A good physics project starts with a question you can test, not with a model to build. "How does a pendulum work?" is a topic. "How does the length of a pendulum affect its period?" is a project: you can change one thing, measure another, and compare your results with theory.

This list gives you 101 physics project ideas in three levels. Each project has a question to answer, a method to follow, the skills it builds, and a way to go further that turns a class exercise into something worth presenting at a science fair.

How to use this list. Projects 1–35 suit beginners and younger students: household materials, simple measurements and clear results. Projects 36–70 add quantitative analysis, graphs, uncertainty and phone or video sensors. Projects 71–101 need school-lab equipment, electronics, programming or public scientific data, and suit senior high school and early university students. You do not have to stay in your level. A beginner project done carefully, with repeated trials and an honest uncertainty estimate, is better than an advanced one done badly.

Many beginner projects grow out of quick demonstrations in our 101 physics experiments you can do at home. We have not run each project for this article; methods follow standard school-lab practice described in the OpenStax textbooks and the tools linked below, and your results will depend on your equipment.

How to plan a physics project

Every project below follows the same structure. Plan these steps before you start:

1. Write a testable question. Name what you will change and what you will measure: "How does X affect Y?"
2. Identify your variables. The independent variable is what you change. The dependent variable is what you measure. Control variables are everything you keep the same.
3. Make a prediction from physics. Use a formula or concept to predict the shape of the result, for example "period should be proportional to the square root of length". Our 100 physics formulas every student should know is a good starting point.
4. Plan your measurements. Choose at least five values of the independent variable, and repeat each measurement at least three times.
5. Estimate uncertainty. Note the precision of your instruments and the spread of your repeated readings. Report results as a value plus or minus an uncertainty.
6. Graph your data. Plot the dependent variable against the independent variable. If theory predicts a straight line when you plot something else (such as $T^2$ against $L$), plot that and find the gradient.
7. Compare with theory and explain differences. Disagreement is not failure. Explaining why your result differs, such as air resistance, friction or heat loss, is often the best part of a project.

Useful free tools

• phyphox, a free app from RWTH Aachen University, reads your phone's accelerometer, gyroscope, magnetometer, light sensor, barometer and microphone, and exports the data.
• Tracker, free open-source video analysis software by Douglas Brown, tracks objects frame by frame in a video and plots position, velocity and acceleration.
• A spreadsheet or Python for graphs, trend lines and averages.
• An Arduino or similar microcontroller for automated sensor readings in advanced projects.

Safety and science fair rules

Check your school's rules and any competition rules before you start. The Regeneron International Science and Engineering Fair (ISEF) requires a risk assessment before experimentation for projects involving hazardous chemicals, activities or devices, and some projects need a qualified supervisor (Society for Science). The rules are updated every year, so use the current edition. In general:

• Get adult or teacher supervision for heat, high voltage, lasers, strong magnets, pressurised containers, cryogenic materials and radiation sources.
• Never work with mains electricity unless a qualified adult designs and supervises the setup.
• Use only radioactive sources supplied and supervised by a school, or natural background radiation.
• Record your safety precautions in your project log; judges look for them.

Beginner projects (1–35)

These need household materials and a ruler, timer, kitchen scale or thermometer.

1. Bounce height and drop height

Question: How does the height a ball is dropped from affect how high it bounces?

Method: Drop a ball from five heights between 0.5 m and 2.0 m in front of a tape measure, filming in slow motion to read the bounce height. Repeat three times at each height.

Skills: Controlled variables, graphing, energy loss.

Go further: Calculate the ratio of bounce height to drop height for different balls and surfaces. That ratio tells you what fraction of the energy survives each bounce.

2. Friction on different surfaces

Question: Which floor surface produces the most friction on a shoe?

Method: Pull a shoe with a spring scale or a rubber band and ruler across carpet, tile, wood and a rubber mat. Record the force needed to keep it moving steadily.

Skills: Measuring force, fair testing.

Go further: Add weights inside the shoe. Plot friction against weight; the gradient is the coefficient of friction for that surface.

3. Paper aeroplane wing shape

Question: How does wing shape affect how far a paper aeroplane flies?

Method: Fold three designs from the same paper. Launch each 10 times from the same height with the same throw, ideally using a simple rubber-band launcher for consistency. Measure distances.

Skills: Reducing variation, averages, aerodynamics.

Go further: Change one feature at a time, such as wing area or a paperclip on the nose, to separate their effects.

4. What affects a pendulum's period?

Question: Does the period of a pendulum depend on its length, its mass or the angle it starts from?

Method: Time 10 swings for at least five lengths, then for three masses at fixed length, then for several starting angles.

Skills: Testing one variable at a time, timing technique.

Go further: Plot period against the square root of length. A straight line confirms $T = 2\pi\sqrt{L/g}$. Notice the period starts to increase slightly at large angles.

5. Parachute size and fall time

Question: How does the area of a parachute affect how long it takes to fall?

Method: Make square parachutes from bin bags with sides from 20 cm to 60 cm, all carrying the same weight. Drop each from the same height and time the fall.

Skills: Drag, area calculations, repeat measurements.

Go further: Test whether fall time depends on area or on side length, by plotting both.

6. Ramp angle and rolling distance

Question: How does the angle of a ramp affect how far a toy car rolls after leaving it?

Method: Release the car from the same point on a ramp set to five angles. Measure the distance it travels across the floor.

Skills: Energy conversion, measuring angles.

Go further: Keep the starting height fixed and change only the angle. Does the car still go further on a steeper ramp?

7. Does mass affect how far a toy car rolls?

Question: If you add mass to a toy car, does it roll further after a ramp?

Method: Tape coins to the car to change its mass, release from a fixed height and measure distance.

Skills: Challenging intuition, friction and inertia.

Go further: Explain your result using energy and the forces that slow the car, such as rolling resistance and air resistance.

8. Balloon rocket distance

Question: How does the amount of air in a balloon affect how far a balloon rocket travels along a string?

Method: Measure balloon circumference to control how much it is inflated. Release along a string track and measure distance.

Skills: Newton's third law, controlling a variable indirectly.

Go further: Compare a level string with one sloping upwards.

9. Rubber-band launcher

Question: How does stretching a rubber band further affect how far it launches a small object?

Method: Mount a rubber band between two nails on a board. Pull it back by measured distances and launch a cotton bud or pom-pom horizontally. Measure the range. Wear safety glasses and never aim at people.

Skills: Elastic potential energy, projectile motion.

Go further: Elastic energy is roughly proportional to the stretch squared. Is the range proportional to the stretch, or to its square?

10. Egg-drop protection

Question: Which packaging design lets an egg survive the greatest drop?

Method: Build containers from fixed materials (paper, straws, tape). Drop each from increasing heights until the egg breaks.

Skills: Impulse, engineering design.

Go further: Film the impacts in slow motion and estimate the stopping time. Longer stopping times mean smaller forces.

11. Best insulator for a hot drink

Question: Which material keeps a cup of hot water warm for longest?

Method: Wrap identical cups in foil, wool, bubble wrap and paper, and leave one bare. Fill each with water at the same starting temperature and record the temperature every 5 minutes for an hour. Adult to pour the hot water.

Skills: Cooling curves, heat transfer.

Go further: Add a lid to one cup to see how much heat escapes by evaporation and convection from the top.

12. Colour and solar heating

Question: Does the colour of a container affect how quickly water inside it warms in sunlight?

Method: Paint or wrap identical jars in black, white, red and silver. Put the same amount of water in each and record temperatures in the sun every 10 minutes.

Skills: Radiation, absorption and reflection.

Go further: Repeat on a cloudy day or under a lamp to compare light sources.

13. What melts ice fastest?

Question: Do salt, sugar and sand melt ice at different rates?

Method: Put equal ice cubes on plates and sprinkle equal masses of each substance on them. Measure the meltwater mass or volume every 10 minutes.

Skills: Freezing point depression, measurement of rates.

Go further: Explain why roads are salted rather than sugared, and why salt stops working in very cold weather.

14. Does salt change boiling point?

Question: How much does adding salt raise the boiling point of water?

Method: With an adult, measure the boiling temperature of pure water, then of water with 1, 2 and 3 tablespoons of salt per litre, using a digital thermometer.

Skills: Precise thermometry, small effects.

Go further: Compare your measured increase with what you would expect from a chemistry textbook. You will find the effect is small, which tests your measurement precision.

15. Which fruits and vegetables float?

Question: Can you predict whether a fruit floats from its density?

Method: Measure each item's mass on a kitchen scale and its volume by displacement in a measuring jug. Calculate density, then test whether it floats.

Skills: Density, displacement method.

Go further: Explain items that float even though they look dense, such as an orange with its peel, compared with the same orange peeled.

16. Clay boat design

Question: Which boat shape carries the most load before sinking?

Method: Use equal amounts of modelling clay to make several hull shapes. Add coins one at a time until each sinks.

Skills: Buoyancy, design iteration.

Go further: Measure each boat's volume and compare its maximum load with Archimedes' principle.

17. Soap and surface tension

Question: How does the amount of soap affect how many water drops fit on a coin?

Method: Make water with 0, 1, 2, 5 and 10 drops of washing-up liquid per cup. Count drops added to a coin before spilling. Repeat five times each.

Skills: Surface tension, dilution series.

Go further: Try salty water, sugary water and water at different temperatures.

18. Capillary action in paper

Question: Which type of paper draws water up highest in 10 minutes?

Method: Hang strips of paper towel, printer paper, newspaper and filter paper with their ends in coloured water. Measure the height reached.

Skills: Capillarity, timing.

Go further: Look at the papers under a magnifier and relate fibre structure to the result.

19. Water level and pitch in bottles

Question: How does the water level in a bottle change the note when you tap it and when you blow across it?

Method: Fill identical bottles to different levels. Use a free tuner or spectrum app to record the frequency for tapping and blowing.

Skills: Sound, resonance, measuring frequency.

Go further: For blowing, plot frequency against the length of the air column above the water.

20. String telephone

Question: How do string type and length affect how well a string telephone carries sound?

Method: Make phones with cotton, nylon fishing line and wire, at several lengths. Play a steady tone into one cup and measure loudness at the other with a phone decibel app.

Skills: Sound transmission, fair testing.

Go further: Test whether pulling the string tighter improves the sound.

21. Soundproofing materials

Question: Which material blocks sound best?

Method: Put a phone playing a fixed tone inside a box, line it with different materials (foam, egg boxes, towels, cardboard) and measure the sound level outside with a second phone.

Skills: Absorption and reflection of sound, decibel scale.

Go further: Test low and high frequencies separately; many materials block high notes better than low ones.

22. Rubber-band guitar

Question: How do tension and length affect the pitch of a plucked rubber band?

Method: Stretch bands over an open box. Change tension by hanging weights from one end, and change length with a moveable bridge. Measure frequency with a tuner app.

Skills: Standing waves, pitch.

Go further: Compare with $f = \frac{1}{2L}\sqrt{T/\mu}$: does frequency go up with the square root of tension?

23. Pinhole size and image sharpness

Question: How does pinhole diameter affect the sharpness and brightness of a pinhole camera image?

Method: Make holes of different sizes in foil. Photograph the image of a bright object on the screen and compare.

Skills: Straight-line propagation of light, trade-offs.

Go further: Very small holes blur the image again because of diffraction. Find the hole size that gives the sharpest image.

24. Shadow size and distance

Question: How does the distance between a light and an object change the size of its shadow?

Method: Shine a small torch at a cardboard shape in front of a wall. Measure the shadow size for several torch distances.

Skills: Similar triangles, measurement.

Go further: Use a large light source and measure the blurry edge (penumbra) as well.

25. Mirrors and multiple images

Question: How does the angle between two mirrors affect the number of images you see?

Method: Hinge two mirrors with tape, set them at measured angles and count images of a small object.

Skills: Reflection, finding a rule from data.

Go further: Test whether the number of images follows $360°/\theta - 1$, and what happens at angles that do not divide 360° evenly.

26. Which liquid bends light most?

Question: Do water, cooking oil, salt water and sugar syrup bend light by different amounts?

Method: Put a coin under a glass of each liquid. Measure the real depth and the apparent depth by looking from directly above with a ruler alongside.

Skills: Refraction, refractive index.

Go further: Refractive index is approximately real depth ÷ apparent depth. Compare your values with published ones.

27. Fruit and vegetable batteries

Question: Which fruit or vegetable produces the highest voltage?

Method: Insert a zinc-coated nail and a copper strip into lemons, potatoes, apples and oranges at a fixed distance apart. Measure the voltage with a multimeter.

Skills: Electrochemical cells, using a multimeter.

Go further: Keep the fruit the same and change the metals or the distance between electrodes.

28. Electromagnet strength

Question: How does the number of turns of wire affect the strength of an electromagnet?

Method: Wind 10, 20, 30, 40 and 50 turns around a nail and count the paperclips it lifts from a single AA battery. Connect only briefly so the wire does not overheat.

Skills: Magnetism, fair testing.

Go further: Compare iron nails, steel bolts and a plastic pen as the core.

29. The triboelectric series

Question: Which pairs of materials produce the strongest static charge when rubbed?

Method: Rub balloons with wool, cotton, plastic and hair for a fixed number of strokes. Measure how far the balloon can lift tiny pieces of paper, or how much it deflects a stream of water.

Skills: Electric charge, designing a measurement.

Go further: Repeat on a humid day and a dry day.

30. Magnets and temperature

Question: Does temperature affect a magnet's strength?

Method: Cool a ceramic fridge magnet in the freezer, warm one in hot tap water (sealed in a bag) and keep one at room temperature. Count paperclips each lifts, or the number of cards it holds a clip through.

Skills: Magnetism, temperature control.

Go further: Research the Curie temperature, above which a magnet loses its magnetism. Do not heat neodymium magnets: they can be permanently weakened and may crack.

31. Oersted's discovery

Question: How does the current in a wire affect how far a nearby compass needle turns?

Method: Run a wire over a compass, aligned north-south. Connect one, then two AA batteries in series with a small resistor (about 10 Ω) for a moment and measure the deflection.

Skills: Magnetic effect of a current, electrical safety.

Go further: Change the distance between wire and compass. The field from a wire falls off as $1/r$.

32. Solar oven design

Question: Which solar oven design reaches the highest temperature?

Method: Build pizza-box ovens with different reflector angles, lining colours and window materials. Measure temperature inside every 10 minutes in full sun.

Skills: Radiation, insulation, design.

Go further: Track the Sun by adjusting the oven every 15 minutes and compare with a fixed oven.

33. Paper helicopter blades

Question: How does blade length affect the fall time of a paper helicopter?

Method: Make helicopters with blades from 4 cm to 12 cm long, using the same paper and one paperclip each. Drop from the same height and time the fall.

Skills: Drag, rotation.

Go further: Find the blade length that gives the longest fall time, and explain why longer is not always better.

34. Spinning top design

Question: How does the shape and mass distribution of a top affect how long it spins?

Method: Make tops from card discs and pencils, varying disc diameter or adding coins at the edge versus the centre. Spin with the same twist and time until they fall.

Skills: Moment of inertia, angular momentum.

Go further: Film from above and count rotations per second in slow motion.

35. Build and calibrate a sundial

Question: How accurately can a homemade sundial tell the time?

Method: Set a stick vertically in flat ground or on a board. Mark the shadow's position every hour on a sunny day, then compare readings with a clock over the following weeks.

Skills: Earth's rotation, angles, long-term observation.

Go further: Notice how readings drift over weeks; research the "equation of time".

Intermediate projects (36–70)

These need graphs, uncertainties and often a phone sensor app, video analysis or a multimeter.

36. Measure g with a pendulum

Question: How precisely can you measure the acceleration due to gravity with a simple pendulum?

Method: Time 20 swings for at least six lengths from 0.3 m to 1.5 m. Plot $T^2$ against $L$; the gradient equals $4\pi^2/g$.

Skills: Linearising data, uncertainty from a gradient.

Go further: Calculate the percentage uncertainty in $g$ and find which measurement contributes most to it.

37. Projectile motion with video analysis

Question: Does a thrown ball follow the parabola predicted by kinematics?

Method: Film a ball thrown across a plain wall with a metre stick in the frame. Track it in Tracker and fit the vertical position to a quadratic.

Skills: Video analysis, curve fitting.

Go further: Compare a heavy ball with a light foam ball. Where does air resistance become visible in the data?

38. Terminal velocity of coffee filters

Question: How does the mass of a falling object affect its terminal velocity?

Method: Stack 1 to 8 paper coffee filters and drop each stack. Use video or a motion sensor to find the steady speed.

Skills: Drag models, graph analysis.

Go further: Plot terminal velocity squared against mass. A straight line suggests drag is proportional to $v^2$.

39. Ball bounce and temperature

Question: How does temperature affect how well a ball bounces?

Method: Bring squash balls or tennis balls to different temperatures in a fridge, at room temperature and in warm water (dried before use). Measure drop and bounce heights quickly.

Skills: Coefficient of restitution, controlling temperature.

Go further: Research why squash players warm the ball up before a game.

40. Damped oscillations

Question: How does the liquid a mass oscillates in affect how quickly the oscillation dies away?

Method: Hang a mass on a spring with its lower half in air, water, then oil. Film it and measure the amplitude of successive swings.

Skills: Damping, exponential decay.

Go further: Plot the logarithm of amplitude against time to find a damping constant for each liquid.

41. Rolling race of shapes

Question: Can you predict which shape rolls down a ramp fastest?

Method: Race a solid cylinder, hollow cylinder, solid ball and hollow ball of similar size. Time each over the same ramp.

Skills: Moment of inertia, energy conservation.

Go further: Calculate predicted times from $I$ for each shape and compare with your measurements.

42. Conservation of momentum in collisions

Question: Is momentum conserved when two carts collide?

Method: Use toy carts or skateboards on a smooth floor, with Velcro for sticky collisions. Film the collisions and measure velocities before and after.

Skills: Momentum, measuring velocity from video.

Go further: Calculate kinetic energy before and after to classify each collision as elastic or inelastic.

43. Rubber band elasticity and hysteresis

Question: Does a rubber band obey Hooke's law, and does it behave the same when unloaded?

Method: Add weights in steps and measure the length, then remove them in steps and measure again.

Skills: Force-extension graphs, non-linear materials.

Go further: The area between the loading and unloading curves is energy lost as heat. Estimate it.

44. Bicycle gears

Question: How does gear ratio affect the speed of a bicycle at a fixed pedalling rate?

Method: Count the teeth on the front chainrings and rear sprockets. Measure the distance travelled per pedal turn for several gears.

Skills: Ratios, rotational motion, real-world measurement.

Go further: Use a phone's GPS or a cycle computer to measure speed at a steady cadence and compare with your predictions.

45. Newton's law of cooling

Question: Does a cup of hot water cool exponentially towards room temperature?

Method: Log the temperature every minute for an hour with a digital thermometer. Plot the logarithm of the temperature difference against time.

Skills: Exponential models, linearisation.

Go further: Compare cooling constants for different cup materials, or with and without a lid.

46. Specific heat capacity of metals

Question: What is the specific heat capacity of aluminium, steel or copper?

Method: Heat a known mass of metal in boiling water (adult), then transfer it to a known mass of cold water in an insulated cup. Measure the final temperature and use $mc\Delta T$ to balance heat lost and gained.

Skills: Method of mixtures, heat loss.

Go further: Estimate how much heat is lost to the cup and air, and correct for it.

47. Latent heat of fusion of ice

Question: How much energy does it take to melt a kilogram of ice?

Method: Add a weighed amount of melting ice (at 0 °C, patted dry with a paper towel) to a known mass of warm water in an insulated cup. Measure temperatures before and after melting.

Skills: Energy balance, latent heat.

Go further: Compare your result with the accepted value of about 334 kJ/kg and identify the main source of error.

48. Thermal conductivity comparison

Question: Which of several rods conducts heat fastest?

Method: Stand rods of copper, aluminium, steel and glass of the same size in hot water. Measure the temperature at the top with a thermometer or a thermal camera over time.

Skills: Conduction, rates of change.

Go further: Rank the rods and compare with published thermal conductivity values.

49. Insulation in a model house

Question: How does insulation thickness affect heat loss from a model house?

Method: Build cardboard boxes with different thicknesses of insulation. Heat each with the same warm water bottle and log the internal temperature drop.

Skills: Heat transfer, engineering trade-offs.

Go further: Add a "window" of cling film to see how much heat it loses compared with an insulated wall.

50. Speed of sound with a resonance tube

Question: What is the speed of sound in air at room temperature?

Method: Hold a tube vertically in a tall jug of water and play a tone of known frequency from a phone above it. Raise the tube until the sound is loudest. That air column is a quarter wavelength (plus a small end correction).

Skills: Resonance, standing waves.

Go further: Use two resonance lengths to cancel the end correction. Measure on a cold and a warm day and compare with $v \approx 331 + 0.6\,T_C$.

51. Measure the Doppler effect

Question: Can you measure a moving source's speed from the Doppler shift?

Method: Play a steady tone from a phone attached to a bicycle or carried by a person riding past a second phone running a frequency analyser. Measure the frequency approaching and leaving.

Skills: Doppler equation, data analysis.

Go further: Calculate the speed from the frequency shift and compare with the speed measured by timing over a known distance.

52. Standing waves on a string

Question: How does tension change the frequencies of standing waves on a string?

Method: Drive a string with a small speaker or vibration motor connected to a phone tone generator. Hang weights to set the tension and find the frequencies that produce 1, 2 and 3 loops.

Skills: Harmonics, wave speed.

Go further: Plot frequency against the square root of tension to test $v = \sqrt{T/\mu}$.

53. Chladni plate patterns

Question: How do vibration patterns on a plate change with frequency?

Method: Fix a thin metal plate at its centre on a speaker. Sprinkle salt on it and sweep the frequency with a tone generator app, photographing each pattern.

Skills: Resonance in two dimensions, observation.

Go further: Compare square and circular plates, or plates of different thicknesses.

54. Bottle resonance

Question: How does the volume of air in a bottle affect the note it makes when you blow across it?

Method: Add water to change the air volume and measure the frequency with a phone app.

Skills: Helmholtz resonance, fitting a model.

Go further: Test whether frequency is proportional to $1/\sqrt{V}$, as the Helmholtz resonator model predicts.

55. Measure refractive index with a laser

Question: What is the refractive index of a glass or acrylic block?

Method: Shine a low-power laser (Class 2, adult supervision) into a rectangular block at several angles on a sheet of paper. Trace the rays and measure angles with a protractor.

Skills: Snell's law, graph of $\sin\theta_1$ against $\sin\theta_2$.

Go further: Measure the critical angle with a semicircular block and compare.

56. Testing the lens equation

Question: Does a magnifying glass obey the thin lens equation?

Method: Form images of a bright object on a screen at different object distances. Measure object and image distances.

Skills: Optics, reciprocal graphs.

Go further: Plot $1/d_i$ against $1/d_o$. The intercepts should both equal $1/f$.

57. Track spacing on a CD or DVD

Question: How far apart are the data tracks on a CD and a DVD?

Method: Shine a laser of known wavelength through or off the disc (adult supervision) onto a wall and measure the angle of the diffraction spots. Use $d\sin\theta = m\lambda$.

Skills: Diffraction gratings, trigonometry.

Go further: Compare your values with the published track pitch of each format.

58. Width of a human hair by diffraction

Question: Can you measure the width of a hair with a laser?

Method: Tape a hair across a frame and shine a laser at it, projecting the pattern on a wall several metres away (adult supervision). Measure the spacing of the dark fringes.

Skills: Single-slit diffraction (by Babinet's principle, a hair diffracts like a slit of the same width).

Go further: Compare hairs from several people and check against a microscope measurement if available.

59. Malus's law

Question: How does the intensity of light through two polarisers depend on the angle between them?

Method: Shine a light through two polarising filters onto a phone's light sensor in phyphox. Rotate one filter in 10° steps.

Skills: Polarisation, cosine relationships.

Go further: Plot intensity against $\cos^2\theta$ to test Malus's law.

60. Ohmic and non-ohmic components

Question: Does a filament bulb obey Ohm's law?

Method: Using a low-voltage supply or batteries, measure current through a resistor and a small filament bulb at several voltages.

Skills: I-V curves, using two meters.

Go further: Explain the bulb's curve by relating its resistance to filament temperature.

61. Internal resistance of a battery

Question: How much internal resistance does an AA battery have, and does it change as the battery runs down?

Method: Connect resistors of several values across the battery, measuring terminal voltage and current each time. Plot voltage against current.

Skills: EMF and internal resistance, straight-line graphs.

Go further: Compare new and used batteries, and different brands or chemistries.

62. Resistance of pencil lines

Question: How does the length and darkness of a pencil line affect its resistance?

Method: Draw graphite strips with pencils from 2H to 6B. Measure resistance with a multimeter at several lengths.

Skills: Resistivity, sample preparation.

Go further: Draw lines of different widths and test whether resistance follows $R = \rho L/A$.

63. Capacitor charging curve

Question: Does a capacitor charge exponentially with a time constant of $RC$?

Method: Charge a large capacitor (such as 1,000 µF) through a resistor from a battery, reading the voltage every few seconds with a multimeter or an Arduino.

Skills: Exponential growth, time constants.

Go further: Repeat with different resistors and plot time constant against $R$.

64. Motor speed and voltage

Question: How does supply voltage affect the speed of a small DC motor?

Method: Run a small hobby motor from one to four AA batteries. Measure its speed using a phone's slow-motion video with a marked paper flag, or a phone's sound spectrum.

Skills: Motors, measuring rotation rate.

Go further: Add a load, such as winding up a string with a weight, and measure the power output.

65. Induced voltage and magnet speed

Question: How does the speed of a magnet through a coil affect the induced voltage?

Method: Drop a magnet through a coil from different heights and record the voltage with a data logger, a microcontroller or a multimeter with a peak hold.

Skills: Faraday's law, data logging.

Go further: Change the number of turns and compare with $\varepsilon = -N\,\Delta\Phi/\Delta t$.

66. Eddy current braking

Question: How does the metal and thickness of a tube affect how slowly a magnet falls through it?

Method: Time a neodymium magnet falling through copper and aluminium tubes of different wall thicknesses (adult for magnets).

Skills: Lenz's law, electrical conductivity.

Go further: Compare a slotted tube with an unslotted one to show that eddy currents cause the effect.

67. Solar panel angle

Question: How does the tilt angle of a small solar panel affect its power output?

Method: Connect a small panel to a resistor and multimeter. Measure power at tilt angles from 0° to 90° at midday.

Skills: Electrical power, angle of incidence.

Go further: Repeat at different times of day and compare the best angle with your latitude.

68. Wind turbine blades

Question: How do the number and angle of turbine blades affect power output?

Method: Build a turbine from a small DC motor (as generator) and card blades. Use a household fan at a fixed distance and measure output voltage across a resistor.

Skills: Energy conversion, engineering optimisation.

Go further: Measure the wind speed with a phone anemometer attachment or by timing a ribbon, and estimate the turbine's efficiency.

69. Measure Earth's magnetic field

Question: What is the strength and direction of Earth's magnetic field where you live?

Method: Use phyphox's magnetometer, away from metal objects, to read the field components. Compare with a model value from NOAA's magnetic field calculator.

Skills: Vector components, sensor calibration.

Go further: Build a tangent galvanometer: a coil with a compass at its centre, where the needle's deflection depends on the ratio of the coil's field to Earth's.

70. Inverse-square law for light

Question: Does the intensity of light fall off with the square of the distance?

Method: In a dark room, measure the illuminance from a small bulb with a phone's light sensor at distances from 0.2 m to 2 m.

Skills: Inverse-square relationships, log-log graphs.

Go further: Plot log intensity against log distance. A gradient of −2 confirms the law; explain deviations close to the bulb.

Advanced projects (71–101)

These need school-lab equipment, electronics, programming, public scientific data or a qualified supervisor.

71. Planck's constant from LEDs

Question: Can you measure Planck's constant using LEDs of different colours?

Method: Find the voltage at which each LED just begins to conduct and glow. Plot that threshold voltage against $1/\lambda$ using each LED's stated wavelength. The gradient equals $hc/e$.

Skills: Semiconductor physics, systematic uncertainty.

Go further: Discuss why defining the "turn-on" point is the largest source of error, and try different methods of finding it from an I-V curve.

72. Speed of light by time of flight

Question: Can you measure the speed of light directly in a school lab?

Method: Send fast light pulses from an LED or laser over a long path, or through a long optical fibre, to a fast photodiode. Measure the delay on an oscilloscope as the path length changes.

Skills: High-speed electronics, timing.

Go further: Measure the speed of light in the fibre and calculate the fibre's refractive index.

73. Cavendish experiment

Question: Can you measure the gravitational constant $G$ with a homemade torsion balance?

Method: Hang a light rod with small lead or steel masses from a thin fibre inside a draught-proof box. Bring large masses close and track the rotation with a laser spot on a distant wall.

Skills: Very small forces, torsion pendulums, long data runs.

Go further: Compare your value with the CODATA value of $6.674 \times 10^{-11}$ N·m²/kg² and identify the main sources of error. Commercial school torsion balances also exist.

74. Eratosthenes: measure Earth's circumference

Question: Can you measure Earth's size with a stick and a shadow?

Method: Partner with a school several hundred kilometres north or south of you. Both measure the length of a vertical stick's shadow at local solar noon on the same day. The difference in Sun angles and the distance between schools give Earth's circumference.

Skills: Geometry, collaboration, historical science.

Go further: Collect data from several partner schools to reduce uncertainty.

75. Cloud chamber

Question: What kinds of particle tracks can you see from background radiation?

Method: Build a diffusion cloud chamber from a clear container, felt soaked in isopropyl alcohol and a metal base cooled with dry ice. Qualified adult supervision only: isopropyl alcohol is flammable and dry ice causes cold burns.

Skills: Particle physics, observation, safety planning.

Go further: Classify tracks by shape (long straight tracks are often muons; short, thick ones are often alpha particles) and count rates over time.

76. Cosmic-ray muons

Question: How does the muon count rate change with shielding, angle or altitude?

Method: Build an open-hardware CosmicWatch detector, developed at MIT, which uses a plastic scintillator and silicon photomultiplier read out over USB (Axani et al., 2018). Log counts in different locations.

Skills: Particle detectors, counting statistics.

Go further: Use two detectors in coincidence to measure how the rate depends on the angle from vertical.

77. Radioactive decay statistics

Question: Do random radioactive decays follow Poisson statistics?

Method: Use a Geiger counter to record counts in many 10-second intervals from background radiation, or from a potassium-rich source such as a "low-sodium" salt substitute (potassium chloride). Build a histogram of the counts.

Skills: Probability distributions, statistics.

Go further: Compare the measured mean and variance; for a Poisson process they should be equal. Only use school-supplied sources under supervision.

78. Spectroscopy of light sources

Question: Can you identify elements from their emission spectra?

Method: Build a spectrometer from a diffraction grating and a phone camera, calibrate it with known lines (such as a fluorescent tube's mercury lines), then measure gas discharge tubes or street lights.

Skills: Atomic spectra, calibration.

Go further: Point it at a white surface lit by sunlight and identify dark Fraunhofer absorption lines.

79. Michelson interferometer

Question: Can you measure a laser's wavelength, or the thermal expansion of a metal, with interference?

Method: Set up a Michelson interferometer (from a school kit, or with mirrors and a beam splitter on a stable base). Move one mirror with a micrometer and count fringes passing a point.

Skills: Interference, precision alignment.

Go further: Attach a mirror to a metal rod and count fringes as it is heated to find its expansion coefficient.

80. Mapping magnetic fields with a Hall sensor

Question: How does the field of a bar magnet or coil vary with distance?

Method: Connect a linear Hall effect sensor to a microcontroller and move it along a ruler away from the magnet or coil.

Skills: Sensors, field models, programming.

Go further: Test whether the field far from a bar magnet falls off as $1/r^3$, as a dipole model predicts.

81. Magnetic levitation with feedback

Question: Can you stabilise a floating magnet with an electromagnet and a control loop?

Method: Use a Hall sensor to measure a magnet's position below an electromagnet, and a microcontroller to adjust the current through a transistor many times per second.

Skills: Control systems, electronics, programming.

Go further: Tune the control constants and plot how the magnet's position responds to a tap.

82. Meissner effect

Question: How does a superconductor interact with a magnet?

Method: Cool a YBCO superconductor disc with liquid nitrogen and place a small magnet above it. Qualified supervision only: liquid nitrogen causes severe cold burns and can displace oxygen in small rooms.

Skills: Superconductivity, cryogenics, safety.

Go further: Measure the levitation height as the disc warms to find when superconductivity stops.

83. Homemade seismometer

Question: Can you detect footsteps, traffic or distant earthquakes with a homemade seismometer?

Method: Suspend a mass on a spring with a magnet that moves inside a coil, and record the coil's voltage with a microcontroller or sound card.

Skills: Oscillators, signal processing.

Go further: Compare your records with nearby seismic stations' public data.

84. Radio astronomy: the hydrogen line

Question: Can you detect the 21 cm radio emission from hydrogen in the Milky Way?

Method: Build a horn antenna and use a low-noise amplifier and a USB software-defined radio to record the spectrum near 1420 MHz while pointing at the galactic plane.

Skills: Radio, spectrum analysis, astronomy.

Go further: Measure Doppler shifts in the hydrogen line at different galactic longitudes to infer the rotation of the galaxy.

85. The Sun's rotation from sunspots

Question: How long does the Sun take to rotate, and does it rotate faster at the equator?

Method: Track sunspots across several days using public images from NASA's Solar Dynamics Observatory (SDO). Never look at the Sun directly or through optics.

Skills: Image analysis, spherical geometry.

Go further: Measure spots at different latitudes to see differential rotation.

86. Exoplanet transit light curves

Question: How big is a planet orbiting another star?

Method: Download a light curve from NASA's TESS mission (mission page), whose data are public through the Mikulski Archive for Space Telescopes (MAST), and measure the depth of the dip during a transit.

Skills: Data analysis, astronomy, programming.

Go further: Use the transit depth and the star's radius to estimate the planet's radius, and the time between transits to find its orbital period.

87. Chaos in a double pendulum

Question: How sensitive is a double pendulum to its starting conditions?

Method: Build a double pendulum from two bars and low-friction bearings. Film several releases from almost the same position, and compare with a numerical simulation.

Skills: Chaos, simulation, video analysis.

Go further: Measure how quickly two nearly identical runs diverge.

88. N-body orbit simulation

Question: Do simulated orbits obey Kepler's laws?

Method: Write a Python program that steps planets forward in time using Newton's law of gravitation and a stable integration method such as velocity Verlet.

Skills: Numerical methods, programming.

Go further: Check energy conservation over long runs with different time steps and integration methods.

89. Projectile with drag: simulation vs reality

Question: How much does air resistance change the path of a thrown ball?

Method: Simulate a projectile with quadratic drag in Python, then film real throws of light and heavy balls and compare.

Skills: Modelling, fitting parameters.

Go further: Fit the drag coefficient that best matches your video data.

90. Monte Carlo radioactive decay

Question: Does random decay of individual nuclei produce an exponential curve?

Method: Simulate a population of nuclei in Python or a spreadsheet, each with a fixed chance of decaying per time step, and plot the number remaining.

Skills: Probability, simulation, exponential models.

Go further: Compare your simulation with real dice-throwing or coin-flipping "decay" by your class.

91. Heat diffusion in a metal rod

Question: Does heat spread along a rod as the diffusion equation predicts?

Method: Heat one end of a metal rod and log temperatures at several points with thermistors and a microcontroller. Simulate the heat equation with finite differences and compare.

Skills: Partial differential equations, data logging.

Go further: Estimate the rod's thermal diffusivity from your fit.

92. Thermoelectric generator efficiency

Question: How does a Peltier module's electrical output depend on the temperature difference across it?

Method: Place a thermoelectric module between hot and cold water baths. Measure the temperature difference and power delivered to a load resistor.

Skills: Thermoelectric effect, efficiency calculations.

Go further: Compare the efficiency with the Carnot limit for the same temperatures.

93. Stirling engine performance

Question: How does the temperature difference across a small Stirling engine affect its speed and power?

Method: Run a low-temperature-difference Stirling engine on cups of water at different temperatures and measure its rotation rate.

Skills: Heat engines, thermodynamic cycles.

Go further: Compare its performance with the Carnot efficiency for each pair of temperatures.

94. Water rocket optimisation

Question: What fraction of water gives a bottle rocket the greatest height?

Method: Launch a rocket from a purpose-made launcher at a fixed pressure with different water volumes. Measure height with a phone altimeter app on board, or by angle measurement from a known distance. Adult supervision, outdoors, eye protection, and never exceed the bottle's safe pressure.

Skills: Momentum, thrust, experimental design.

Go further: Model the flight numerically and compare with your measurements.

95. Homemade wind tunnel

Question: How does shape affect drag coefficient?

Method: Build a small wind tunnel from a fan, a honeycomb of straws to smooth the flow and a clear test section. Measure drag on shapes using a kitchen scale or force sensor.

Skills: Fluid dynamics, force measurement.

Go further: Compare a flat plate, sphere, cylinder and teardrop shape at several speeds.

96. Acoustic levitation

Question: How does the spacing of ultrasonic standing-wave nodes compare with the wavelength?

Method: Build TinyLev, an open-source acoustic levitator from the University of Bristol made of 40 kHz ultrasonic transducers and a 3D-printed frame (Marzo, Barnes and Drinkwater, 2017). Levitate small polystyrene beads and measure the gap between them.

Skills: Standing waves, ultrasound, electronics.

Go further: Calculate the speed of sound from the node spacing and the transducer frequency.

97. Brownian motion

Question: Can you measure the random motion of tiny particles and relate it to temperature?

Method: Film diluted milk or microspheres under a microscope (a phone clip-on microscope can work). Track individual particles and calculate their mean squared displacement over time.

Skills: Statistical physics, particle tracking.

Go further: Use the Stokes–Einstein relation to estimate Boltzmann's constant from your data, and discuss your uncertainty.

98. Charge-to-mass ratio of the electron

Question: What is the ratio $e/m$ for an electron?

Method: Use a school fine-beam tube with Helmholtz coils. Measure the radius of the electron beam's circular path for different accelerating voltages and coil currents.

Skills: Magnetic forces on charges, high-voltage lab safety.

Go further: Plot $r^2$ against $V$ and get $e/m$ from the gradient. Compare with the CODATA value. Teacher supervision required.

99. The photoelectric effect

Question: How does the stopping voltage depend on light frequency?

Method: Use a school photoelectric apparatus with filters or LEDs of known wavelength. Measure the voltage that just stops the photocurrent for each.

Skills: Quantum physics, linear fits.

Go further: Find Planck's constant from the gradient and the work function from the intercept, and compare with project 71.

100. Solar cell I-V curve and temperature

Question: How does temperature affect a solar cell's output and efficiency?

Method: Sweep a variable resistor across a small solar cell under a fixed lamp and record current and voltage. Repeat with the cell warmed or cooled.

Skills: Semiconductor devices, maximum power point.

Go further: Find the maximum power point at each temperature and explain why output falls as panels heat up.

101. Gravitational waves from open data

Question: Can you find a black hole merger signal in real detector data?

Method: Follow the Python tutorials from the Gravitational Wave Open Science Center to download LIGO strain data around a published event, filter it and plot a time-frequency spectrogram.

Skills: Signal processing, astrophysics, scientific programming.

Go further: Estimate the "chirp" frequency change and relate it to the masses of the merging objects.

Writing up and presenting your project

Judges and teachers look for the same things:

• A clear question and hypothesis, stated at the start.
• A method someone else could repeat, with diagrams and a list of equipment.
• Raw data and processed data, in tables with units and uncertainties.
• Graphs with labelled axes and units, with error bars where you can estimate them.
• An honest conclusion that answers the question and compares your result with theory.
• An evaluation of weaknesses in your method and what you would improve.
• References for any formulas, accepted values or methods you used.

Common mistakes

• Too many variables changed at once, so you cannot tell what caused the result.
• Only one trial at each setting, which hides random error.
• No uncertainty estimate, so nobody can judge whether your result agrees with theory.
• Choosing a topic, not a question. "Magnets" is a topic; "How does temperature affect a magnet's strength?" is a project.
• Building something without measuring anything. A working model is good engineering, but a physics project needs data.

Where to go next

• Revise the ideas behind these projects in 100 physics concepts explained with real-world examples.
• Find the equations you need in 100 physics formulas every student should know.
• Look for project ideas in the devices around you with 100 applications of physics in everyday life.
• For projects 88–91, our 101 NumPy examples cover the Python numerical tools you need.
• Browse more articles and blogs in the physics category.

References

• University Physics Volumes 1–3, Samuel J. Ling, Jeff Sanny, William Moebs and others, OpenStax (2016). https://openstax.org/details/books/university-physics-volume-1
• College Physics 2e, Paul Peter Urone and Roger Hinrichs, OpenStax (2022). https://openstax.org/details/books/college-physics-2e
• "Hazardous Chemicals, Activities or Devices", ISEF International Rules, Society for Science. https://www.societyforscience.org/isef/international-rules/hazardous-chemicals-activities-or-devices/
• phyphox, RWTH Aachen University. https://phyphox.org/
• Tracker Video Analysis and Modeling Tool, Douglas Brown, Open Source Physics. https://physlets.org/tracker/
• S. N. Axani, K. Frankiewicz and J. M. Conrad, "The CosmicWatch Desktop Muon Detector: a self-contained, pocket sized particle detector", Journal of Instrumentation 13, P03019 (2018). https://arxiv.org/abs/1801.03029
• A. Marzo, A. Barnes and B. W. Drinkwater, "TinyLev: A multi-emitter single-axis acoustic levitator", Review of Scientific Instruments 88, 085105 (2017). https://doi.org/10.1063/1.4989995
• Gravitational Wave Open Science Center, tutorials. https://gwosc.org/tutorials/
• "TESS (Transiting Exoplanet Survey Satellite)", NASA Science. https://science.nasa.gov/mission/tess/
• Solar Dynamics Observatory, NASA Goddard Space Flight Center. https://sdo.gsfc.nasa.gov/
• "Magnetic Field Calculators", NOAA National Centers for Environmental Information. https://www.ngdc.noaa.gov/geomag/calculators/magcalc.shtml
• "Fundamental Physical Constants: 2022 CODATA values", NIST Physical Measurement Laboratory. https://physics.nist.gov/cuu/Constants/