A Level Core Practicals
A-Level Physics Practicals
This document covers the core practical procedures across the A-Level Physics course, organized by module.
Module 3: Mechanics
1. Investigating Motion and Collisions
Focuses on verifying momentum conservation or investigating the relationship between force and acceleration.
Equipment
Trolleys or air track gliders
Air track or friction-compensated ramp
Light gates and a digital data logger
Interrupter cards (of known length)
Masses and string (if investigating $F=ma$)
Method & Data Analysis
Set up the air track or ramp. If using a ramp, tilt it slightly to compensate for friction.
Attach an interrupter card to the trolley and set up two light gates.
For a collision, place one trolley at rest and launch the second toward it.
Record initial velocity ($u$) and final velocities ($v$) using light gates.
Measure the mass of each trolley.
Data Analysis: Compare initial momentum ($m_1u_1 + m_2u_2$) to final momentum ($m_1v_1 + m_2v_2$).
Data Analysis: Calculate kinetic energy ($1/2mv^2$) to determine if the collision was elastic.
Improving Accuracy
Use an air track to eliminate friction.
Ensure interrupter cards are vertical and measured precisely.
Repeat measurements and calculate a mean.
Safety
Use a "catch box" to stop trolleys falling.
Securely attach masses to the string.
2. Determining Acceleration of Free Fall ($g$)
Measuring $g$ using a falling object and electronic timing.
Equipment
Electromagnet and steel ball bearing
Trapdoor and base unit
Electronic timer or data logger
Metre ruler and plumb line
Method & Data Analysis
Position the electromagnet at height ($h$) above the trapdoor.
Release the ball; the timer starts on release and stops when the trapdoor is hit.
Repeat for at least five different heights.
Data Analysis: Use $h = 1/2gt^2$ (from $s = ut + 1/2at^2$ where $u=0$).
Data Analysis: Plot $h$ vs $t^2$. Gradient = $g/2$.
Improving Accuracy
Use a small, dense ball to minimize air resistance.
Measure height from the bottom of the ball to the top of the trapdoor.
Safety
Switch off electromagnet when not in use.
Keep floor clear of trip hazards.
3. Determining Terminal Velocity in Fluids
Investigating motion when drag force equals weight.
Equipment
Large transparent cylinder
Viscous liquid (Glycerol or heavy oil)
Steel ball bearings (varying sizes)
Stopwatch and rubber bands (for markers)
Method & Data Analysis
Mark equal intervals on the cylinder using rubber bands.
Drop the ball bearing into the center.
Record time at each marker; constant time between markers indicates terminal velocity.
Data Analysis: Calculate $v = \Delta s / \Delta t$.
Data Analysis: Plot velocity vs time; the plateau is terminal velocity.
Improving Accuracy
Drop in the center to avoid "wall effects."
Use a tall enough cylinder to ensure terminal velocity is reached.
Use video analysis for more precise timing.
Safety
Clean spills immediately (slippery).
Wear goggles to prevent splashes.
4. Experimental Determination of Centre of Gravity
Using the principle of moments to locate the balancing point.
Equipment
Irregularly shaped flat object (lamina)
Plumb line (string and weight)
Clamp stand, pin, and pencil
Method & Data Analysis
Make three holes near the edges of the lamina.
Suspend the lamina and plumb line from a pin through one hole.
Mark the path of the plumb line on the lamina.
Repeat for other holes.
Data Analysis: The intersection of the lines is the centre of gravity.
Improving Accuracy
Ensure the lamina swings freely.
Use a thin, sharp pencil for lines.
Space holes widely around the perimeter.
Safety
Take care with pins to avoid finger pricks.
Secure the clamp stand to the desk.
5. Investigating Force-Extension Characteristics
Applying Hooke’s Law to determine material stiffness.
Equipment
Helical spring, rubber band, or polythene strip
Clamp stand and slotted masses
Millimetre ruler and set square
Method & Data Analysis
Measure original length ($l_0$).
Add masses in increments, recording the new length ($l$).
Calculate extension $x = l - l_0$.
Unload masses to check for plastic deformation.
Data Analysis: Plot Force vs Extension.
Data Analysis: Gradient of linear section is the spring constant ($k$) where $F = kx$.
Improving Accuracy
Use a set square to avoid parallax error.
Wait for oscillations to stop before reading.
Safety
Wear goggles in case the spring snaps.
Use a padded box under masses to protect feet.
Module 4: Electrons, Waves, and Photons
6. Determining the Young Modulus
Determining stiffness by measuring the ratio of tensile stress to tensile strain.
Equipment
Long, thin metal wire
G-clamp, pulley, and slotted masses
Micrometer and travelling microscope
Method & Data Analysis
Measure wire diameter in several places to find average area ($A$).
Measure original length ($L$) from clamp to marker.
Add masses and measure extension ($\Delta L$) using a travelling microscope.
Data Analysis: Calculate stress ($\sigma = F/A$) and strain ($\varepsilon = \Delta L/L$).
Data Analysis: Plot Stress vs Strain. Gradient = Young Modulus ($E$).
Improving Accuracy
Use a long wire (3m+) for larger extensions.
Ensure the wire is straight and free of kinks.
Safety
Wear goggles; wire can whip if it snaps.
Use a padded box for falling weights.
7. Investigating Electrical Characteristics (I-V)
Examining how current varies with potential difference across components.
Equipment
Variable DC power supply or rheostat
Ammeter and Voltmeter
Components: Resistor, filament lamp, diode, thermistor
Method & Data Analysis
Connect component in series with ammeter and variable resistor.
Connect voltmeter in parallel across the component.
Vary potential difference and record $I$ and $V$.
Reverse connections for negative readings.
Data Analysis: Plot $I$ vs $V$.
Improving Accuracy
Use a potential divider for better control at low voltages.
Switch off between readings to prevent heating.
Safety
Components can become hot; avoid touching during operation.
8. Determining the Resistivity of a Metal
Calculating material-specific property independent of dimensions.
Equipment
Resistance wire and micrometer
Ammeter, Voltmeter, and metre ruler
Jockey or crocodile clips
Method & Data Analysis
Measure wire diameter to find area ($A$).
Vary the length ($L$) of wire in the circuit.
Record Resistance ($R = V/I$) for each length.
Data Analysis: Plot $R$ vs $L$. Gradient = $\rho/A$.
Data Analysis: $\rho = \text{gradient} \times A$.
Improving Accuracy
Pull wire taut against the ruler.
Use low current to minimize heating.
Safety
Wire can become very hot; do not touch while power is on.
9. Determining Internal Resistance
Investigating terminal voltage drop under load.
Equipment
Cell, variable resistor, and switch
Ammeter and Voltmeter
Method & Data Analysis
Record e.m.f. ($\varepsilon$) with switch open ($I=0$).
Close switch and vary current ($I$) using the variable resistor.
Record terminal voltage ($V$) and $I$.
Data Analysis: Use $V = \varepsilon - Ir$.
Data Analysis: Plot $V$ vs $I$. y-intercept = $\varepsilon$, magnitude of gradient = $r$.
Improving Accuracy
Use a new battery for stable readings.
Close switch only briefly for each reading.
Safety
Avoid short circuits to prevent cell damage or leaks.
10. Investigating Potential Divider Circuits
Creating specific output voltages using resistor combinations.
Equipment
Power supply, fixed resistors
Thermistor or LDR
Voltmeter, water bath/lamp
Method & Data Analysis
Set up two components in series.
Measure $V_{out}$ across one component.
Vary temperature (thermistor) or light (LDR).
Data Analysis: Compare to $V_{out} = V_{in} \times (R_2 / (R_1 + R_2))$.
Improving Accuracy
Keep thermometer and thermistor close together.
Measure distance to light source for LDR.
Safety
Keep water away from power supplies.
11. Using an Oscilloscope to Determine Frequency
Measuring time periods to calculate wave frequency.
Equipment
Oscilloscope (CRO)
Signal generator
Method & Data Analysis
Connect signal generator to CRO.
Adjust Time-base to see at least one full cycle.
Measure horizontal divisions for one cycle.
Calculate Period ($T$) = divisions $\times$ Time-base.
Data Analysis: Frequency $f = 1/T$.
Improving Accuracy
Measure across multiple cycles and divide.
Align cycle start with a major grid line.
Safety
Ensure equipment is PAT tested.
12. Demonstrating Wave Effects in a Ripple Tank
Visualizing reflection, refraction, and diffraction.
Equipment
Ripple tank, motor-driven dipper
Strobe light
Barriers and glass blocks
Method & Data Analysis
Set up shallow water and constant dipper frequency.
Use strobe to "freeze" waves.
Use barriers for reflection/diffraction and glass blocks for refraction.
Data Analysis: Measure $\lambda$; calculate $v = f\lambda$.
Improving Accuracy
Use a strobe for stable measurements.
Ensure tank is level and on a damped surface.
Safety
Keep water away from electricity.
Be aware of strobe sensitivity (epilepsy).
13. Observing Polarising Effects
Demonstrating transverse wave planes.
Equipment
Microwave transmitter/receiver and metal grille
Light source and polarising filters
Method & Data Analysis
Light: Rotate one filter relative to another; observe intensity changes.
Microwaves: Rotate metal grille between transmitter and receiver.
Data Analysis: Note absorption when wires are parallel to electric field oscillation.
Improving Accuracy
Use a digital light sensor.
Keep metal objects away from microwave path.
Safety
Do not look directly at high-intensity light.
14. Investigating Refraction and Total Internal Reflection
Mapping light paths across media boundaries.
Equipment
Ray box, glass blocks (rectangular and semi-circular)
Protractor and paper
Method & Data Analysis
Trace block outline and entry/exit rays.
Measure angles of incidence ($i$) and refraction ($r$).
For TIR, use semi-circular block and increase $i$ until refraction disappears.
Data Analysis: Plot $\sin i$ vs $\sin r$. Gradient = $n$.
Data Analysis: Verify $n = 1 / \sin C$.
Improving Accuracy
Use a thin ray and sharp pencil.
Use a large protractor.
Safety
Ray boxes get hot; turn off when not in use.
15. Superposition Experiments
Investigating interference patterns from coherent sources.
Equipment
Two speakers/Laser/Microwaves
Double-slit slide and screen
Method & Data Analysis
Shine laser through double-slit.
Measure slit separation ($d$), distance to screen ($D$), and fringe width ($w$).
Data Analysis: $\lambda = \frac{dw}{D}$.
Improving Accuracy
Ensure $D$ is large ($2\text{m}+$).
Measure across several fringes and divide.
Safety
Laser Safety: Never look directly into the beam.
16. Determining the Wavelength of Light
Using diffraction to measure nanometer-scale wavelengths.
Equipment
Laser, diffraction grating
Metre ruler and tape measure
Method & Data Analysis
Shine laser through grating onto screen.
Measure distance to screen ($D$) and distance to maxima ($x$).
Calculate slit separation $d$ from lines per mm.
Data Analysis: Use $d \sin \theta = n\lambda$ where $\tan \theta = x/D$.
Improving Accuracy
Large $D$ reduces percentage uncertainty.
Measure between orders (e.g., $+1$ to $-1$) and divide.
Safety
Standard laser safety protocols.
17. Observing Stationary Waves
Demonstrating interference forming nodes and antinodes.
Equipment
Vibration generator, signal generator
String, pulley, and weights
Method & Data Analysis
Vary frequency until a standing wave forms.
Find harmonics.
Data Analysis: Node-to-node distance = $\lambda/2$.
Data Analysis: Calculate $v = f\lambda$.
Improving Accuracy
Use a sharp bridge for the fixed end.
Repeat for multiple harmonics.
Safety
Wear goggles in case the string snaps.
18. Determining the Speed of Sound in Air
Using resonance in a closed pipe.
Equipment
Resonance tube, cylinder of water
Tuning forks, metre ruler
Method & Data Analysis
Hold vibrating fork over tube and raise from water until resonance.
Measure air column length ($L$).
Data Analysis: First resonance $L + c = v/4f$ ($c$ is end correction).
Data Analysis: Plot $L$ vs $1/f$. Gradient = $v/4$.
Improving Accuracy
Average length from raising and lowering.
Perform end correction.
Safety
Mop up water spills.
19. Determining the Planck Constant ($h$)
Using LED "turn-on" voltage.
Equipment
LEDs of different wavelengths
Power supply, voltmeter, resistor
Method & Data Analysis
Increase voltage until LED just glows; record threshold $V_0$.
Repeat for different colors.
Data Analysis: $eV_0 = hc/\lambda$.
Data Analysis: Plot $V_0$ vs $1/\lambda$. Gradient = $hc/e$.
Improving Accuracy
Use a dark room to see initial glow.
Extrapolate $I-V$ graph to $I=0$.
Safety
Do not exceed LED current rating.
20. Demonstration of the Photoelectric Effect
Evidence for light as a particle.
Equipment
Gold-leaf electroscope, zinc plate
UV lamp, emery paper
Method & Data Analysis
Clean zinc plate and place on negatively charged electroscope.
Shine UV; leaf falls as electrons emit.
Repeat with glass (absorbs UV) or positive charge (no emission).
Data Analysis: $hf = \Phi + KE_{max}$.
Improving Accuracy
Ensure zinc is freshly sanded.
Use a dry room.
Safety
UV Safety: Wear UV-filtering goggles; do not look at lamp.
Module 5: Newtonian World and Astrophysics
21. Experimental Evidence of Electron Diffraction
Demonstrating wave-like nature of electrons.
Equipment
Electron diffraction tube
EHT power supply
Method & Data Analysis
Accelerate electrons through graphite target.
Measure diffraction ring diameters ($D$) on screen.
Data Analysis: Calculate $\lambda = \frac{h}{\sqrt{2meV}}$.
Data Analysis: Verify with $n\lambda = d \sin \theta$.
Improving Accuracy
Darkened room for visibility.
Measure at multiple voltages.
Safety
High Voltage: Do not touch terminals.
Fragile Vacuum: Handle tube with care.
22. Observing Brownian Motion
Evidence for kinetic theory of gases.
Equipment
Smoke cell, microscope, lamp
Method & Data Analysis
Seal smoke in cell and illuminate from side.
Observe random, jerky motion under microscope.
Data Analysis: Conclude bombardment by invisible air molecules.
Improving Accuracy
Ensure cell is airtight.
Let lamp warm up to avoid convection.
Safety
Use matches/smoke in ventilated area.
23. Determining Specific Heat Capacity
Measuring energy to raise material temperature.
Equipment
Metal block, immersion heater, thermometer
Ammeter, Voltmeter, Stopwatch, Insulation
Method & Data Analysis
Measure mass ($m$) and insulate block.
Record Temperature vs Time while heating.
Data Analysis: $E = VIt$.
Data Analysis: $P = mc \times (\Delta \theta / \Delta t)$.
Improving Accuracy
Use oil in holes for thermal contact.
Measure max temperature after heater is off.
Safety
Heater gets very hot; use only when submerged.
24. Determining Specific Latent Heat
Energy for change of state at constant temperature.
Equipment
Ice/Water, immersion heaters, balances
Method & Data Analysis
Use a "test" and "control" setup for melting ice.
Measure mass melted by heater ($m = m_{test} - m_{control}$).
Data Analysis: $L_f = VIt / m$.
Improving Accuracy
Ensure ice is at $0\text{°C}$.
Steady boil for vaporisation.
Safety
Avoid steam burns and keep water from electronics.
25. Investigating Gas Laws
Exploring P, V, and T relationships.
Equipment
Boyle’s Law apparatus, constant volume bulb
Pressure gauge, water bath
Method & Data Analysis
Boyle: Plot $P$ vs $1/V$.
Pressure: Plot $P$ vs $T$ (Celsius); extrapolate to $P=0$ for absolute zero.
Improving Accuracy
Change volume slowly (isothermal).
Submerge entire gas volume in water bath.
Safety
Do not exceed pressure limits.
26. Investigating Circular Motion
Relationship between force, mass, velocity, and radius.
Equipment
Rubber bung, tube, string, masses
Stopwatch, balance, ruler
Method & Data Analysis
Whirl bung in horizontal circle with hanging mass providing centripetal force ($F=Mg$).
Maintain constant radius ($r$) and record time for 20 rotations.
Data Analysis: Calculate $v = 2\pi r / T$.
Data Analysis: Plot $F$ vs $v^2$. Gradient = $m/r$.
Improving Accuracy
Use slow-motion camera for rotations.
Whirl as horizontally as possible.
Safety
Clear "no-go" zone for swinging bung.
Wear goggles.
27. Determining Period/Frequency of SHM
Factors affecting oscillating systems.
Equipment
Masses, spring or pendulum
Stopwatch, fiducial marker
Method & Data Analysis
Displace mass and record time for 20 oscillations.
Vary mass (spring) or length (pendulum).
Data Analysis (Spring): Plot $T^2$ vs $m$. Gradient = $4\pi^2/k$.
Data Analysis (Pendulum): Plot $T^2$ vs $L$. Gradient = $4\pi^2/g$.
Improving Accuracy
Use fiducial marker at equilibrium.
Small angles ($<10^\circ$) for pendulum.
Safety
Padded catch box for falling masses.
Module 6: Particles and Medical Physics
28. Investigating Capacitors in Combination
Verifying series and parallel rules.
Equipment
Capacitors, multimeters
Method & Data Analysis
Measure $C_{total}$ for series and parallel arrangements.
Data Analysis: Parallel $C_{total} = \sum C$; Series $1/C_{total} = \sum 1/C$.
Improving Accuracy
Account for zero error of meter.
Safety
Check polarity of electrolytic capacitors.
29. Investigating Capacitor Charge and Discharge
Exponential decay of voltage/current.
Equipment
Capacitor, resistor, DC source, stopwatch
Method & Data Analysis
Charge capacitor then discharge through resistor.
Record $V$ vs time.
Data Analysis: Plot $\ln V$ vs $t$. Gradient = $-1/RC$.
Data Analysis: Time constant $\tau$ is time to fall to $37%$.
Improving Accuracy
Use high-resistance voltmeter.
Safety
Capacitors store energy; discharge safely.
30. Determining Magnetic Flux Density ($B$)
Using a current balance to measure force.
Equipment
Magnets, top-pan balance, stiff wire
Power supply, ammeter
Method & Data Analysis
Place magnets on balance and tare.
Run current through wire between magnets.
Record mass change ($\Delta m$) for different currents ($I$).
Data Analysis: $F = \Delta mg$. Plot $F$ vs $I$. Gradient = $BL$.
Improving Accuracy
Wire must be perfectly perpendicular to field.
Use high-precision balance.
Safety
Strong magnets (keep away from cards/pacemakers).
31. Investigating Magnetic Flux with Search Coils
Mapping field strength and orientation.
Equipment
Search coil, solenoid, signal generator, CRO
Method & Data Analysis
Place search coil in solenoid with AC field.
Record induced e.m.f. ($V_0$).
Vary angle ($\theta$) or position.
Data Analysis: $V_0 \propto BAN\omega$.
Improving Accuracy
High frequency for larger e.m.f.
Keep away from other metal objects.
Safety
Do not let solenoid overheat.
32. Investigating Transformers
Turn ratios and voltage relationships.
Equipment
C-cores, copper wire, AC supply, voltmeters
Method & Data Analysis
Wrap primary and secondary coils on C-cores.
Measure $V_p$ and $V_s$ for different $N_s$.
Data Analysis: $\frac{V_s}{V_p} = \frac{N_s}{N_p}$.
Improving Accuracy
Clamp cores tightly.
Laminated cores reduce losses.
Safety
Low Voltage AC Only.
33. Absorption of Alpha, Beta, and Gamma Radiation
Testing penetrating power.
Equipment
Sources, G-M tube and counter
Absorbers: Paper, Aluminum, Lead
Method & Data Analysis
Measure background count.
Measure count rate with source and different absorbers.
Data Analysis: Use corrected count rate (Total - Background).
Improving Accuracy
Long counting times.
Constant source-tube distance.
Safety
Time, Distance, Shielding. Use forceps.
34. Determining the Half-Life of an Isotope
Measuring decay rate over time.
Equipment
Protactinium generator, G-M tube, data logger
Method & Data Analysis
Shake generator and record count rate every 10s.
Data Analysis: Plot corrected count rate vs time.
Data Analysis: Find time to halve ($t_{1/2}$). Or plot $\ln(\text{Count Rate})$ vs $t$; gradient = $-\lambda$.
Improving Accuracy
Start readings immediately after shaking.
Safety
Sealed source but handle with care.
35. Simulation of Radioactive Decay
Statistical model using dice.
Equipment
Large number of dice
Method & Data Analysis
Roll dice and remove those showing a "6".
Record remaining dice ($N$) vs throw number ($t$).
Data Analysis: Plot $N$ vs $t$ for exponential curve.
Data Analysis: Verify $\lambda = 1/6$.
Improving Accuracy
Use large starting number (500+).
