Welcome to the AQA GCSE Physics Required Practicals Guide
In AQA GCSE Physics (8463), at least 15% of your total exam marks come directly from questions based on practical work. You won't be tested while carrying out the experiments in a lab; instead, written exam questions will ask you to describe methods, identify variables, explain sources of error, and interpret graphs and data—often in slightly new or unfamiliar contexts.
There are exactly ten required practicals in the separate science Physics specification. Practicals 1, 3, 4, 5, 6, 7, 8, and 10 are shared with Combined Science, while Practicals 2 and 9 are physics only. Let's break down each practical step by step, focusing on what you do, what you measure, and how to avoid classic exam pitfalls.
Note: For broader skills such as calculating means, plotting graphs, handling uncertainties, and categorising errors, please see the other chapters in this section (such as "Accuracy, precision, errors and evaluation" and "Data handling, graphs and calculations").
---Practical 1: Specific Heat Capacity
Aim of the Experiment
To determine the specific heat capacity of one or more materials (typically a solid metal block such as aluminium, copper, or iron).
Key Apparatus
Metal block with two pre-drilled holes, electric immersion heater, 12 V power supply, ammeter, voltmeter, connecting leads, thermometer, stopwatch, digital balance, and thermal insulation (such as bubble wrap or foam).
Method Step-by-Step
1. Measure the mass: Place the metal block on a balance to determine its mass \(m\) in kilograms (\(\text{kg}\)).
2. Insulate the block: Wrap the block in insulating material to reduce unwanted thermal energy transfers to the surroundings.
3. Set up the equipment: Place the immersion heater into the larger hole in the block and insert the thermometer into the smaller hole. Add a few drops of water or oil to the thermometer hole to ensure good thermal contact.
4. Build the circuit: Connect the immersion heater in series with a power supply and an ammeter. Connect a voltmeter in parallel across the heater.
5. Record baseline: Read and record the initial temperature of the block.
6. Heat and record: Switch on the power supply, start the stopwatch, and record the current \(I\) and potential difference \(V\). Take temperature readings at regular intervals (e.g. every minute) for 10 minutes.
7. Post-heating maximum: Switch off the heater. Keep observing the thermometer for a few minutes; the temperature will continue to rise briefly as thermal energy conducts throughout the block. Record the highest temperature reached.
Key Equations & Calculations
The electrical energy transferred to the heater is:
\(E = P \times t = V \times I \times t\)
The specific heat capacity \(c\) is calculated using the formula:
\(\Delta E = m \times c \times \Delta \theta \implies c = \frac{\Delta E}{m \times \Delta \theta}\)
where \(\Delta E\) is energy transferred in joules (\(\text{J}\)), \(m\) is mass in kilograms (\(\text{kg}\)), \(c\) is specific heat capacity in joules per kilogram per degree Celsius (\(\text{J/kg}\,^\circ\text{C}\)), and \(\Delta \theta\) is temperature change in degrees Celsius (\(^\circ\text{C}\)).
Common Errors & Exam Tips
Calculated value is too high: A classic exam question asks why your experimental value of \(c\) is higher than the textbook value. The answer is thermal energy is dissipated to the surroundings rather than heating the block. Therefore, the measured \(\Delta \theta\) is smaller than it should be for the energy supplied, making the calculated \(c\) too large.
Memory trick: Remember to wrap your block like a winter coat—insulation stops energy escaping!
Key Takeaway: Ensure good thermal contact, insulate the block, and calculate electrical energy using \(E = V \times I \times t\).
---Practical 2: Thermal Insulation (Physics Only)
Aim of the Experiment
To investigate the effectiveness of different materials as thermal insulators and to investigate factors affecting thermal insulation properties (such as the number of layers of an insulator).
Investigation A: Testing Different Materials
1. Prepare containers: Take several identical small beakers or metal cans. Wrap each one in a different insulating material of the same thickness (e.g. newspaper, wool, bubble wrap, corrugated cardboard). Keep one container uninsulated as a control.
2. Add hot water: Boil water using a kettle and carefully pour equal volumes of hot water into each container.
3. Seal and monitor: Cover each container with an insulating lid (with a small hole for a thermometer) to prevent energy loss by evaporation. Record the starting temperature of the water.
4. Time the cooling: Start the stopwatch and record the temperature of each container at fixed intervals (e.g. every 2 or 3 minutes) for 15–20 minutes.
5. Compare: The material that produces the smallest temperature drop over the time period is the most effective insulator.
Investigation B: Testing Thickness (Number of Layers)
Keep the material constant (e.g. newspaper) and wrap identical beakers with 1, 2, 4, and 6 layers. Repeat the hot-water cooling procedure. As the thickness increases, the rate of cooling decreases because the thermal resistance increases.
Key Variables to Control
• Starting temperature of the water.
• Volume of water added to each container.
• Surface area of the container exposed to the surroundings.
• Ambient (room) temperature.
Key Takeaway: Good thermal insulators have low thermal conductivity and slow down the rate of cooling; always use a lid to stop evaporation.
---Practical 3: Factors Affecting Resistance
Aim of the Experiment
To use circuit diagrams to set up and check circuits investigating:
Activity A: The effect of the length of a wire on its resistance at constant temperature.
Activity B: The arrangement of resistors in series and parallel.
Activity A: Wire Length vs. Resistance
1. Circuit setup: Connect a power supply (d.c.), a switch, an ammeter, and a length of resistance wire attached to a metre rule in series. Connect a voltmeter in parallel across the test section of the wire using crocodile clips.
2. Measure: Attach the crocodile clips at a distance of \(0.10\,\text{m}\) (\(10\,\text{cm}\)). Close the switch, immediately record the current \(I\) and potential difference \(V\), and switch off immediately to prevent the wire from heating up.
3. Repeat: Move the clips to increase the length in steps of \(0.10\,\text{m}\) up to \(1.00\,\text{m}\), recording \(I\) and \(V\) each time.
4. Calculate: Calculate resistance for each length using \(R = \frac{V}{I}\).
5. Graph: Plot resistance (\(y\)-axis) against length (\(x\)-axis). The graph should give a straight line through the origin, showing that resistance is directly proportional to wire length.
Activity B: Resistors in Series and Parallel
1. Series: Connect two identical known resistors in series with a power supply and an ammeter. Measure total current \(I\) and total potential difference \(V\). Calculate total resistance \(R_{\text{total}} = \frac{V}{I}\). The total resistance is greater than that of any individual resistor (\(R_{\text{total}} = R_1 + R_2\)).
2. Parallel: Reconnect the two identical resistors in parallel. Measure total current and potential difference. Calculate total resistance. The total resistance of two resistors in parallel is less than the resistance of either single resistor because adding parallel loops provides additional pathways for the current.
Crucial Exam Hazards & Control
Heating of the wire: As current flows, electrical work transfers energy into the thermal store of the wire. Increasing temperature increases resistance, making the test unfair. Control: Use low currents and turn the switch off between readings.
Key Takeaway: Resistance is directly proportional to wire length (\(R \propto L\)); adding resistors in series increases total resistance, while adding them in parallel decreases total resistance.
---Practical 4: \(I\text{--}V\) Characteristics
Aim of the Experiment
To construct circuits and determine the current–potential difference (\(I\text{--}V\)) characteristics of a resistor at constant temperature, a filament lamp, and a diode.
Circuit Setup & Operation
Connect a d.c. power supply, a switch, an ammeter, a variable resistor (or variable power supply), and the component under test in series. Connect a voltmeter in parallel across the component.
1. Vary potential difference: Adjust the variable resistor to change the potential difference across the component. Record pairs of readings from the ammeter and voltmeter.
2. Reverse polarity: Switch off, reverse the battery/power pack connections, and repeat the measurements to obtain negative values of potential difference and current.
3. Plot: Plot current \(I\) on the vertical axis against potential difference \(V\) on the horizontal axis.
Component Characteristics Explained
• Ohmic conductor (resistor at constant temperature): The \(I\text{--}V\) graph is a straight line passing through the origin. Current is directly proportional to potential difference (\(V = I \times R\)), meaning resistance remains constant.
• Filament lamp: The graph is an S-shaped curve passing through the origin. As potential difference increases, current increases, causing the filament to get hotter. Higher temperature increases the vibrations of the metal ions, which increases resistance. Thus, the curve flattens at higher voltages.
• Diode: Current flows in only one direction (the forward direction). It has very high resistance in the reverse direction (practically zero current). In the forward direction, current only starts to flow after a small threshold potential difference is reached (around \(0.6\text{--}0.7\,\text{V}\)), after which resistance drops sharply and current rises steeply. A protective resistor is always placed in series with a diode to prevent excessive currents.
Key Takeaway: An ohmic conductor has constant resistance; a filament lamp's resistance increases with temperature; a diode conducts current easily in one direction only.
---Practical 5: Determining Density
Aim of the Experiment
To determine the densities of regular solid objects, irregular solid objects, and liquids using direct measurements and displacement techniques.
Core Formula
\(\rho = \frac{m}{V}\)
where \(\rho\) is density in kilograms per cubic metre (\(\text{kg/m}^3\)) or grams per cubic centimetre (\(\text{g/cm}^3\)), \(m\) is mass in \(\text{kg}\) or \(\text{g}\), and \(V\) is volume in \(\text{m}^3\) or \(\text{cm}^3\).
1. Regular Solids (e.g. Cubes, Rectangular Prisms)
• Mass: Measure the mass using a digital top-pan balance (zero the balance first).
• Volume: Measure dimensions (length, width, height) using a ruler, micrometer, or Vernier callipers. Calculate volume using \(V = \text{length} \times \text{width} \times \text{height}\).
• Density: Divide mass by volume.
2. Irregular Solids (Displacement Method / Eureka Can)
• Mass: Measure the mass of the dry object using a balance.
• Volume: Fill a displacement can (Eureka can) with water until it reaches the spout. Allow excess water to drip out into a waste beaker until dripping stops.
• Place a clean, dry measuring cylinder beneath the spout.
• Carefully submerge the irregular solid on a thin thread without splashing.
• Collect the displaced water. The volume of water displaced into the cylinder equals the volume of the solid object.
• Density: Divide the dry mass by this measured volume.
3. Liquids
• Place an empty measuring cylinder on a balance and zero it (press the tare button). Alternatively, record the mass of the empty cylinder.
• Pour a known volume of liquid (e.g. \(50\,\text{cm}^3\)) into the measuring cylinder.
• Read the liquid level at eye level from the bottom of the meniscus to avoid parallax error.
• Record the mass of the liquid directly from the tared balance (or subtract the mass of the empty cylinder).
• Calculate \(\rho = \frac{m}{V}\).
Key Takeaway: Regular volumes are calculated from measured dimensions; irregular volumes are found by measuring the volume of water displaced.
---Practical 6: Force and Extension of a Spring
Aim of the Experiment
To investigate the relationship between force and extension for a spring and determine its spring constant.
Apparatus Setup
Clamp stand, two clamps, boss heads, helical spring, metre rule, pointer (fiducial marker), slotted mass hanger and masses, heavy G-clamp to secure the stand to the bench.
Method Step-by-Step
1. Secure the stand: Clamp the base of the stand to the bench with a G-clamp to prevent it from toppling over.
2. Align scale: Hang the spring from the top clamp. Attach a horizontal pointer to the bottom of the spring and set up the vertical metre rule beside it.
3. Initial position: Record the initial ruler reading of the pointer with no added load. This is the unloaded length \(L_0\).
4. Add load: Hang a mass hanger (e.g. \(0.10\,\text{kg}\), which exerts a weight of approximately \(1.0\,\text{N}\) since \(W = m \times g\)) onto the spring.
5. Record and calculate: Record the new position \(L\) of the pointer at eye level. Calculate extension:
\(e = L - L_0\)
6. Increment: Add masses in steps of \(0.10\,\text{kg}\) up to around \(0.50\text{--}0.70\,\text{kg}\), recording the extension at each step.
7. Plot: Plot force applied (\(F\), in newtons, on the \(y\)-axis) against extension (\(e\), in metres, on the \(x\)-axis).
Interpreting the Graph
• The straight-line portion passing through the origin demonstrates Hooke's Law: force is directly proportional to extension (\(F \propto e\)).
• The gradient of the linear section of the \(F\text{--}e\) graph gives the spring constant \(k\):
\(F = k \times e \implies k = \frac{F}{e} = \text{gradient}\)
• If the graph curves, the spring has exceeded its limit of proportionality and will undergo inelastic deformation (it will not return to its original length when unloaded).
Key Takeaway: Force is directly proportional to extension up to the limit of proportionality; the gradient of the linear \(F\text{--}e\) graph is the spring constant \(k\).
---Practical 7: Acceleration and Newton's Second Law
Aim of the Experiment
To investigate the effect of:
Part A: Varying force on the acceleration of an object of constant mass.
Part B: Varying mass on the acceleration of an object under a constant force.
Equipment Setup
A dynamics trolley on a horizontal runway connected by a light string over a pulley to a hanging mass holder; light gates connected to a data logger (or a ticker timer) to measure acceleration accurately without human reaction time errors.
Part A: Varying Force with Constant Total Mass
Important Principle: The accelerating force is provided by the weight of the hanging masses (\(F = m_{\text{hanging}} \times g\)). However, Newton's Second Law (\(F = m \times a\)) applies to the entire system (trolley + string + hanging masses).
• Start with several small slotted masses placed on top of the trolley.
• Release the trolley and record its acceleration through the light gates.
• To increase the accelerating force, move one mass from the trolley to the hanging holder. Do not add new masses from the bench; moving masses transfers force while keeping the total mass of the system constant.
• Repeat for several values of hanging force.
• Plot acceleration (\(y\)-axis) against accelerating force (\(x\)-axis). The graph is a straight line through the origin, showing \(a \propto F\).
Part B: Varying Mass with Constant Accelerating Force
• Keep the hanging mass on the holder constant so the pulling force remains unchanged.
• Add masses directly to the trolley to increase total system mass.
• Record acceleration for each mass setting.
• Plot acceleration (\(y\)-axis) against system mass (\(x\)-axis) to show an inverse relationship, or plot acceleration against \(\frac{1}{\text{mass}}\) to obtain a straight line through the origin, showing \(a \propto \frac{1}{m}\).
Friction Compensation
Friction between the trolley wheels and the track opposes motion. To compensate, slightly tilt the ramp until the trolley rolls down at constant speed when given a gentle push (gravity cancels friction).
Key Takeaway: Accelerating force must be changed by transferring masses between the trolley and the hanger to keep total system mass constant.
---Practical 8: Wave Properties (Ripple Tank & Solid String)
Aim of the Experiment
To make observations and take measurements to determine the frequency, wavelength, and speed of waves in a liquid (ripple tank) and waves in a solid (vibrating string).
Activity A: Waves in a Liquid (Ripple Tank)
1. Setup: A shallow tank of water with a motorized wooden dipper oscillating at a constant frequency. A lamp above projects the wave crest shadows onto a white card underneath the tank.
2. Wavelength (\(\lambda\)): Place a ruler on the card beneath the waves. Because moving wave shadows are difficult to measure, take a photograph of the shadows alongside the ruler. Measure the distance across multiple wave crests (e.g. 10 crests) and divide by the number of wave intervals to find the wavelength.
3. Frequency (\(f\)): Count the number of waves passing a fixed point in 10 seconds using a stopwatch, then divide by 10. Alternatively, read the frequency directly from the signal generator driving the dipper.
4. Wave Speed (\(v\)): Calculate wave speed using the wave equation:
\(v = f \times \lambda\)
Alternatively, measure the time \(t\) it takes for a single wave crest to travel the known length \(s\) of the tank, and calculate speed using \(v = \frac{s}{t}\).
Activity B: Waves in a Solid (Vibrating String)
1. Setup: Connect a vibration generator to a signal generator. Tie one end of a string to the vibration generator and pass the other end over a pulley, loaded with hanging masses to keep the string taut.
2. Create standing waves: Switch on the signal generator and adjust the frequency until a clear, stable standing wave with distinct nodes (points of zero amplitude) and antinodes (points of maximum amplitude) is formed.
3. Wavelength (\(\lambda\)): Measure the total distance across as many complete loops as possible with a metre rule. Two complete loops form one full wavelength. Thus:
\(\text{Wavelength } \lambda = \frac{\text{Total length of loops}}{\text{Number of loops}} \times 2\)
4. Wave Speed (\(v\)): Read frequency \(f\) from the signal generator and calculate speed using \(v = f \times \lambda\).
Key Takeaway: Measure across multiple wave crests or standing wave loops to minimise measurement uncertainty, and use \(v = f \times \lambda\).
---Practical 9: Reflection and Refraction of Light (Physics Only)
Aim of the Experiment
To investigate the reflection of light by different types of surfaces and the refraction of light by different substances.
Activity A: Reflection by Different Surfaces
1. Setup: Place a plain sheet of paper on a board. Place a plane mirror on the paper and draw a line along its reflecting edge. Draw a normal line at \(90^\circ\) to this reflecting line.
2. Trace rays: Use a ray box with a narrow slit to direct a single ray of light at the point where the normal meets the mirror. Trace the incident ray and the reflected ray onto the paper with small pencil crosses.
3. Measure: Remove the mirror, join the crosses to the normal point using a ruler, and measure the angle of incidence (\(i\)) and the angle of reflection (\(r\)) with a protractor (both measured relative to the normal).
4. Compare surfaces: Replace the smooth mirror with different materials (e.g. rough paper, dull metal). A smooth plane surface produces specular reflection where \(i = r\); rough surfaces produce diffuse reflection where light is scattered in many directions.
Activity B: Refraction in Different Substances
1. Setup: Place a rectangular block of transparent material (such as perspex or glass) on a piece of paper and trace its outline.
2. Shine ray: Direct a narrow ray of light from a ray box at an angle into one face of the block. Mark pencil crosses along the incident ray, the ray exiting the opposite face, and draw a line connecting them inside the block.
3. Construct normals: Remove the block. Draw normal lines (\(90^\circ\)) at the points where the ray enters and leaves the block.
4. Measure angles: Measure the angle of incidence (\(i\)) in air and the angle of refraction (\(r\)) inside the block.
5. Findings: When entering a more dense medium (air to glass), light slows down and bends towards the normal (\(i > r\)). When emerging into a less dense medium (glass to air), it speeds up and bends away from the normal.
6. Compare: Repeat with different transparent materials (e.g. perspex vs glass) to compare their optical densities and degrees of refraction.
Key Takeaway: All angles of incidence, reflection, and refraction must be measured from the ray to the normal line (\(90^\circ\) to the surface), never to the surface itself.
---Practical 10: Infrared Emission and Absorption
Aim of the Experiment
To investigate how the amount of infrared radiation absorbed or emitted by a surface depends on the nature of that surface.
Activity A: Emission of Infrared (Leslie's Cube)
1. Apparatus: A Leslie's cube is a hollow metal cube with four vertically facing sides painted with different surfaces: typically matt black, shiny black, white, and shiny silver (or bare metal).
2. Procedure: Place the Leslie's cube on a heat-proof mat. Fill the cube with boiling water from a kettle and put the lid on.
3. Detection: Point an infrared detector (or thermal imaging camera / infrared thermometer) at each of the four faces from the same fixed distance (e.g. \(10\,\text{cm}\)). Measure the infrared intensity emitted by each face.
4. Results:
• Matt black emits the greatest intensity of infrared radiation.
• Shiny silver emits the lowest intensity of infrared radiation.
Activity B: Absorption of Infrared
1. Setup: Mount two identical metal plates vertically at equal distances on either side of an infrared radiant heater. One plate is coated in matt black, and the other has a shiny silver surface.
2. Attachment: Stick a small coin or drawing pin to the outside face of each plate using a small blob of candle wax.
3. Observation: Turn on the heater. Both plates receive the same intensity of radiation. The wax on the back of the matt black plate melts first, causing its coin to drop off before the coin on the shiny silver plate.
4. Conclusion: Matt black surfaces are the best absorbers of infrared radiation; shiny silver surfaces reflect infrared and absorb poorly.
Key Surface Comparisons
• Matt black: Best emitter, best absorber, worst reflector.
• Shiny silver: Worst emitter, worst absorber, best reflector.
Key Takeaway: Matt black surfaces emit and absorb infrared radiation most effectively; shiny metallic surfaces are poor emitters, poor absorbers, and excellent reflectors.
---High-Yield Practical Skills & Exam Checklist
When revising these 10 practicals for Paper 1 and Paper 2, ask yourself these essential questions for every single experiment:
• Independent variable: What am I deliberately changing?
• Dependent variable: What am I measuring as an outcome?
• Control variables: What must be kept constant to make it a fair test?
• Resolution: What is the smallest division on my measuring tool (e.g. \(1\,\text{mm}\) on a metre rule, \(0.01\,\text{s}\) on a stopwatch)?
• Safety hazards: What could cause harm (e.g. boiling water causing scalds, hot wires burning skin, heavy weights falling on toes), and how do we minimise the risk (e.g. clamp stands, heat-resistant mats, handle with care)?
• Repeatability: Did you repeat each measurement at least three times, discard anomalies, and calculate a mean?