# 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** 1. Set up the air track or ramp. If using a ramp, tilt it slightly to compensate for friction. 2. Attach an interrupter card to the trolley and set up two light gates. 3. For a collision, place one trolley at rest and launch the second toward it. 4. Record initial velocity ($u$) and final velocities ($v$) using light gates. 5. Measure the mass of each trolley. 6. **Data Analysis:** Compare initial momentum ($m\_1u\_1 + m\_2u\_2$) to final momentum ($m\_1v\_1 + m\_2v\_2$). 7. **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** 1. Position the electromagnet at height ($h$) above the trapdoor. 2. Release the ball; the timer starts on release and stops when the trapdoor is hit. 3. Repeat for at least five different heights. 4. **Data Analysis:** Use $h = 1/2gt^2$ (from $s = ut + 1/2at^2$ where $u=0$). 5. **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** 1. Mark equal intervals on the cylinder using rubber bands. 2. Drop the ball bearing into the center. 3. Record time at each marker; constant time between markers indicates terminal velocity. 4. **Data Analysis:** Calculate $v = \\Delta s / \\Delta t$. 5. **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** 1. Make three holes near the edges of the lamina. 2. Suspend the lamina and plumb line from a pin through one hole. 3. Mark the path of the plumb line on the lamina. 4. Repeat for other holes. 5. **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** 1. Measure original length ($l\_0$). 2. Add masses in increments, recording the new length ($l$). 3. Calculate extension $x = l - l\_0$. 4. Unload masses to check for plastic deformation. 5. **Data Analysis:** Plot Force vs Extension. 6. **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** 1. Measure wire diameter in several places to find average area ($A$). 2. Measure original length ($L$) from clamp to marker. 3. Add masses and measure extension ($\\Delta L$) using a travelling microscope. 4. **Data Analysis:** Calculate stress ($\\sigma = F/A$) and strain ($\\varepsilon = \\Delta L/L$). 5. **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** 1. Connect component in series with ammeter and variable resistor. 2. Connect voltmeter in parallel across the component. 3. Vary potential difference and record $I$ and $V$. 4. Reverse connections for negative readings. 5. **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** 1. Measure wire diameter to find area ($A$). 2. Vary the length ($L$) of wire in the circuit. 3. Record Resistance ($R = V/I$) for each length. 4. **Data Analysis:** Plot $R$ vs $L$. Gradient = $\\rho/A$. 5. **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** 1. Record e.m.f. ($\\varepsilon$) with switch open ($I=0$). 2. Close switch and vary current ($I$) using the variable resistor. 3. Record terminal voltage ($V$) and $I$. 4. **Data Analysis:** Use $V = \\varepsilon - Ir$. 5. **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** 1. Set up two components in series. 2. Measure $V\_{out}$ across one component. 3. Vary temperature (thermistor) or light (LDR). 4. **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** 1. Connect signal generator to CRO. 2. Adjust Time-base to see at least one full cycle. 3. Measure horizontal divisions for one cycle. 4. Calculate Period ($T$) = divisions $\\times$ Time-base. 5. **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** 1. Set up shallow water and constant dipper frequency. 2. Use strobe to "freeze" waves. 3. Use barriers for reflection/diffraction and glass blocks for refraction. 4. **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** 1. **Light:** Rotate one filter relative to another; observe intensity changes. 2. **Microwaves:** Rotate metal grille between transmitter and receiver. 3. **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** 1. Trace block outline and entry/exit rays. 2. Measure angles of incidence ($i$) and refraction ($r$). 3. For TIR, use semi-circular block and increase $i$ until refraction disappears. 4. **Data Analysis:** Plot $\\sin i$ vs $\\sin r$. Gradient = $n$. 5. **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** 1. Shine laser through double-slit. 2. Measure slit separation ($d$), distance to screen ($D$), and fringe width ($w$). 3. **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** 1. Shine laser through grating onto screen. 2. Measure distance to screen ($D$) and distance to maxima ($x$). 3. Calculate slit separation $d$ from lines per mm. 4. **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** 1. Vary frequency until a standing wave forms. 2. Find harmonics. 3. **Data Analysis:** Node-to-node distance = $\\lambda/2$. 4. **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** 1. Hold vibrating fork over tube and raise from water until resonance. 2. Measure air column length ($L$). 3. **Data Analysis:** First resonance $L + c = v/4f$ ($c$ is end correction). 4. **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** 1. Increase voltage until LED just glows; record threshold $V\_0$. 2. Repeat for different colors. 3. **Data Analysis:** $eV\_0 = hc/\\lambda$. 4. **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** 1. Clean zinc plate and place on negatively charged electroscope. 2. Shine UV; leaf falls as electrons emit. 3. Repeat with glass (absorbs UV) or positive charge (no emission). 4. **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** 1. Accelerate electrons through graphite target. 2. Measure diffraction ring diameters ($D$) on screen. 3. **Data Analysis:** Calculate $\\lambda = \\frac{h}{\\sqrt{2meV}}$. 4. **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** 1. Seal smoke in cell and illuminate from side. 2. Observe random, jerky motion under microscope. 3. **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** 1. Measure mass ($m$) and insulate block. 2. Record Temperature vs Time while heating. 3. **Data Analysis:** $E = VIt$. 4. **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** 1. Use a "test" and "control" setup for melting ice. 2. Measure mass melted by heater ($m = m\_{test} - m\_{control}$). 3. **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** 1. **Boyle:** Plot $P$ vs $1/V$. 2. **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** 1. Whirl bung in horizontal circle with hanging mass providing centripetal force ($F=Mg$). 2. Maintain constant radius ($r$) and record time for 20 rotations. 3. **Data Analysis:** Calculate $v = 2\\pi r / T$. 4. **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** 1. Displace mass and record time for 20 oscillations. 2. Vary mass (spring) or length (pendulum). 3. **Data Analysis (Spring):** Plot $T^2$ vs $m$. Gradient = $4\\pi^2/k$. 4. **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** 1. Measure $C\_{total}$ for series and parallel arrangements. 2. **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** 1. Charge capacitor then discharge through resistor. 2. Record $V$ vs time. 3. **Data Analysis:** Plot $\\ln V$ vs $t$. Gradient = $-1/RC$. 4. **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** 1. Place magnets on balance and tare. 2. Run current through wire between magnets. 3. Record mass change ($\\Delta m$) for different currents ($I$). 4. **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** 1. Place search coil in solenoid with AC field. 2. Record induced e.m.f. ($V\_0$). 3. Vary angle ($\\theta$) or position. 4. **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** 1. Wrap primary and secondary coils on C-cores. 2. Measure $V\_p$ and $V\_s$ for different $N\_s$. 3. **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** 1. Measure background count. 2. Measure count rate with source and different absorbers. 3. **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** 1. Shake generator and record count rate every 10s. 2. **Data Analysis:** Plot corrected count rate vs time. 3. **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** 1. Roll dice and remove those showing a "6". 2. Record remaining dice ($N$) vs throw number ($t$). 3. **Data Analysis:** Plot $N$ vs $t$ for exponential curve. 4. **Data Analysis:** Verify $\\lambda = 1/6$. **Improving Accuracy** - Use large starting number (500+).