1028 science project ideas, from class 1 to college.

What it shows

A falling magnet induces eddy currents in the copper pipe. By Lenz’s law these currents make a magnetic field that opposes the motion, so the magnet falls far more slowly than a non-magnetic object.

You will need

• A strong neodymium magnet
• A copper or aluminium pipe
• A non-magnetic object of similar size for comparison
• A stopwatch

Safety: Neodymium magnets snap together and can pinch. Keep them away from phones, pacemakers and young children.

Take it further: Time the fall through pipes of different thickness or length.

What it shows

A coin under water looks raised, because light bends as it leaves the water. The refractive index is the real depth divided by the apparent depth, so different liquids give different values.

You will need

• A tall clear glass or beaker
• A coin and a scale
• Water, glycerine and cooking oil
• A travelling microscope in the lab, or pins and careful sighting

What it shows

Piezoelectric discs make a small voltage when they are pressed. Many discs under a tile, with a rectifier and a capacitor, can light LEDs, though the energy from each step is very small.

You will need

• Piezo discs
• Diodes for a bridge rectifier
• A capacitor
• LEDs
• Plywood tiles and foam

What it shows

The resistance of a wire is directly proportional to its length and inversely proportional to its area of cross section (R = rho L / A). Doubling the length doubles R, and twisting two equal wires together halves it.

You will need

• About 2 m of nichrome heater wire (from an electrical repair shop, under Rs 40) or thin iron binding wire
• A metre scale and a wooden plank to tape the wire along
• Two AA cells in a holder
• A digital multimeter
• Crocodile clip leads
• A screw gauge from the lab, or the wire gauge printed on the packet

Safety: Nichrome gets warm when current flows; keep the circuit closed only while reading. Cut wire with pliers, not a knife, and an adult must help with the cut ends, which are sharp.

Take it further: Repeat with wires of two different gauges and plot R against 1/A for a fixed length.

What it shows

The terminal voltage of a cell falls as it supplies more current because of its internal resistance, following V = E minus I r. A graph of V against I is a straight line whose intercept is the emf E and whose slope is minus r.

You will need

• One fresh and one used AA or D cell
• Five resistors: 4.7, 10, 22, 47 and 100 ohm (1 W or 2 W, from an electronics shop)
• A digital multimeter
• Crocodile clip leads
• Graph paper

Safety: Never short the cell directly with a wire; it heats fast. Keep each reading under ten seconds so the cell does not warm up or run down during the experiment.

Take it further: Measure r of two cells in series and in parallel and compare with the expected 2r and r/2.

What it shows

Pure water barely conducts, but dissolved salt gives free ions that carry current. The current through a salt solution rises with concentration at first and then levels off as the ions crowd each other.

You will need

• Two carbon rods pulled from dead zinc-carbon cells (an adult must open them) or two graphite pencil leads
• Common salt, a teaspoon and a kitchen weighing scale
• A 250 ml measuring jug and five identical glasses
• Three AA cells in a holder
• A digital multimeter
• Crocodile clip leads and a cardboard strip to hold the rods 3 cm apart

Safety: Cells only. Do not use the solutions afterwards for anything else. Wash hands after handling the carbon rods and wipe up spills, since salt water corrodes metal.

Take it further: Repeat at 10, 25 and 40 degrees Celsius for one concentration to show that conductivity of a solution rises with temperature.

What it shows

A current flowing through a magnet in a magnetic field feels a sideways force (F = B I L), and here that force makes the magnet and screw spin at hundreds of revolutions per minute. It is the simplest motor that works with no coil and no commutator.

You will need

• One AA cell
• A 5 cm steel screw or nail
• A small disc neodymium magnet, 10 to 15 mm (about Rs 30 from an online shop)
• A 15 cm piece of copper wire with the insulation stripped
• A second magnet and a paper cup for the extension

Safety: The cell is shorted while the motor runs and gets hot; run it only for 10 to 20 seconds at a time. Neodymium magnets snap together hard and pinch, and small ones must be kept away from young children. Cells only.

Take it further: Build a wire homopolar motor where a bent copper loop spins around the cell instead of the magnet.

What it shows

Moving a magnet through a coil changes the magnetic flux through it and induces an emf (Faraday’s law), which lights an LED with no cell at all. Faster shaking and more turns give a brighter flash.

You will need

• A 15 cm length of PVC or a thick ballpoint pen barrel, 15 to 20 mm wide
• About 40 m of enamelled copper wire, 32 to 36 SWG (about Rs 150)
• A strong neodymium rod or stack of disc magnets that slides freely inside the tube
• Two LEDs (red works best, it needs only about 1.8 V)
• Two bottle caps or rubber stoppers to close the ends
• Tape, sandpaper and a multimeter set to AC volts

Safety: Keep neodymium magnets away from phones, cards and small children. Sand the enamel outdoors or over a bin. No cells are needed, so there is nothing to short.

Take it further: Add a diode bridge and a 1 F supercapacitor so the torch stores charge and stays lit after shaking stops.

What it shows

A solid aluminium or copper plate swinging between magnet poles stops within a few swings, while a slotted plate swings on, because circulating eddy currents are induced in the solid plate and Lenz’s law makes them oppose the motion. This is how train and roller-coaster magnetic brakes work.

You will need

• Two aluminium sheets about 8 cm by 8 cm, 1 to 2 mm thick (an old cooking pot lid or a sheet from a scrap shop); one left solid, one cut into comb slots
• Two strong neodymium block magnets or a stack of discs
• A wooden stand with a crossbar and a long bolt as a pivot
• A ruler, a protractor and a stopwatch or phone
• Glue and a small clamp

Safety: An adult must cut the slots with a hacksaw and file the edges smooth. Keep the magnets apart from each other when not fitted; they pinch fingers.

Take it further: Slide a magnet down a sloped aluminium sheet and down a slotted sheet and time both to show the same effect in a different form.

What it shows

Two different metals joined at two points produce a small voltage when the two junctions are at different temperatures (the Seebeck effect). The voltage rises roughly in proportion to the temperature difference, which is how thermocouple thermometers work.

You will need

• 30 cm of bare copper wire and 30 cm of iron binding wire (or a steel paper clip straightened)
• A digital multimeter that reads millivolts
• A cup of ice water and a cup of hot water from a kettle
• A kitchen or lab thermometer
• Sandpaper and a small pair of pliers

Safety: An adult must handle the hot water and the kettle. Do not put the junction into a flame; hot water up to 90 degrees Celsius is enough for a clear reading.

Take it further: Join ten copper-iron pairs in series as a thermopile and show that the voltage is ten times larger.

What it shows

An LED only begins to conduct above a threshold voltage that is higher for colours of shorter wavelength: red about 1.8 V, green about 2.1 V, blue about 2.8 V. The threshold energy e V roughly equals the photon energy h c / lambda, so this experiment gives an estimate of Planck’s constant.

You will need

• Red, yellow, green, blue and white 5 mm LEDs (about Rs 2 each)
• A 10 kilo-ohm potentiometer (variable resistor)
• Three AA cells in a holder (4.5 V)
• A 220 ohm resistor
• A digital multimeter
• A breadboard or crocodile clips, and graph paper

Safety: Keep the 220 ohm resistor in series always, or the LED burns out. Never look straight into the blue or white LED at full brightness. Cells only.

Take it further: Measure the LED voltage in the dark with a bright torch shining on it to show the small photovoltaic effect in reverse.

What it shows

A capacitor charging through a resistor reaches 63 percent of the supply voltage after one time constant tau = R C, and discharges to 37 percent in the same time. With a large capacitor and a large resistor the process takes tens of seconds, slow enough to time by hand and to plot.

You will need

• A 1000 microfarad, 16 V electrolytic capacitor (about Rs 10)
• Resistors of 10, 22 and 47 kilo-ohm
• Three AA cells in a holder (4.5 V)
• A digital multimeter on DC volts
• A stopwatch or phone
• A red LED and a 220 ohm resistor for the discharge demonstration
• A breadboard or crocodile clips

Safety: Connect the electrolytic capacitor with its marked negative stripe to the negative side of the cells; reversed, it can heat and burst. Discharge it through a resistor before handling. Cells only.

Take it further: Use the discharge curve to measure an unknown resistor, or an unlabelled capacitor, from the measured time constant.

What it shows

A Wheatstone bridge is balanced when the galvanometer shows zero, and then the unknown resistance equals the known one multiplied by the ratio of the two wire lengths (X = R l / (100 minus l)). A home-built metre bridge measures resistors to within a few percent.

You will need

• A 1 m length of 28 SWG nichrome or constantan wire
• A 1.1 m wooden plank with a paper metre scale glued on
• Three brass or copper strips with screw terminals (an electrician can supply strips), or large crocodile clips
• A centre-zero galvanometer from the lab, or a multimeter on its lowest DC millivolt range
• Two AA cells, a switch and a jockey (a sharpened wire on a wooden handle)
• Known resistors: 10, 22, 47 and 100 ohm and one unmarked resistor

Safety: Cells only. Press the jockey briefly rather than sliding it, so the wire is not scraped thin. An adult must fix the terminal strips with screws.

Take it further: Measure the resistance of a coil of wire at room temperature and in hot water to find its temperature coefficient of resistance.

What it shows

A compass at the centre of a vertical coil set in the magnetic north-south plane is deflected by the coil’s field, and the tangent of the deflection angle is proportional to the current (tan theta = B_coil / B_H). This measures current and even the horizontal component of Earth’s field.

You will need

• A cardboard ring or plastic lid about 15 cm across for the coil frame
• About 15 m of enamelled copper wire for 20 to 30 turns
• A plotting compass with a degree scale, or a small compass placed on a printed protractor
• Resistors of 22, 47, 100 and 220 ohm
• Two AA cells in a holder and a switch
• A multimeter on milliamps
• A wooden base and a spirit level or a smartphone level app

Safety: Cells only, and keep the current below about 100 mA so the coil stays cool. Keep steel objects and phones well away from the compass during readings.

Take it further: Repeat with 10 and 40 turns and show the slope changes in proportion to N.