Required Practicals

AQA GCSE Physics has 10 required practicals that you must know in detail. You will be examined on these through questions about the method, equipment, variables, expected results, graphing, errors, and safety. You do not need to have performed every practical yourself, but you must be able to describe and explain each one as if you had. Required practical questions can appear on either Paper 1 or Paper 2, depending on the topic.

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Why Required Practicals Matter

• Approximately 15% of the marks across both papers are based on practical skills (assessed through written questions)
• Questions can ask you to describe the method, explain the choice of equipment, identify variables, plot or interpret graphs, evaluate the method, and suggest improvements
• You will often be given data from a practical you have not seen before and asked to apply the same skills

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Required Practical 1: Specific Heat Capacity

Topic: Energy (Paper 1)

Aim

To measure the specific heat capacity of a material (usually a metal block or water).

Equipment

• Metal block (e.g., aluminium) with two holes (one for the heater, one for the thermometer)
• Immersion heater
• Thermometer or temperature sensor
• Joulemeter (or ammeter, voltmeter, and stopwatch to calculate energy: E = V x I x t)
• Insulation (lagging)
• Balance (to measure mass)
• Power supply

Method

1. Measure the mass of the metal block using a balance.
2. Insert the immersion heater into one hole and the thermometer into the other.
3. Wrap the block in insulation to reduce energy losses.
4. Record the initial temperature.
5. Switch on the heater and record the energy supplied (using a joulemeter) and the temperature at regular intervals.
6. After heating for a set time, switch off the heater and record the maximum temperature reached.
7. Calculate: c = E / (m x change_in_T).

Variables

Variable	Type
Energy supplied (or time)	Independent
Temperature change	Dependent
Mass of block, material, voltage, insulation	Control

Expected Results

• Temperature increases as more energy is supplied.
• The calculated specific heat capacity should be close to the accepted value (e.g., aluminium: 900 J/kg degC).
• Experimental values are usually higher than the accepted value because energy is lost to the surroundings.

Graph Work

• Plot temperature (y-axis) against energy supplied or time (x-axis).
• The graph should be a straight line through the origin if losses are minimal.
• The gradient can be used to calculate specific heat capacity.

Common Errors and Improvements

Error	Improvement
Energy lost to surroundings	Use better insulation (lagging)
Poor thermal contact between heater and block	Add thermal paste or oil to the heater hole
Temperature continues to rise after heater is switched off	Wait for the maximum temperature to be reached before recording
Inaccurate energy measurement	Use a joulemeter rather than calculating from V, I, and t

Safety

• The metal block and heater become very hot — use tongs or heat-proof gloves.
• Do not touch the heater or block during or immediately after the experiment.
• Ensure the power supply is switched off before adjusting equipment.

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Required Practical 2: Thermal Insulation

Topic: Energy (Paper 1)

Aim

To investigate how the type or thickness of insulation affects the rate of cooling.

Equipment

• Beakers (same size)
• Thermometers or temperature sensors
• Insulating materials (e.g., bubble wrap, felt, newspaper, cotton wool)
• Hot water
• Measuring cylinder (to measure equal volumes of water)
• Stopwatch
• Lids (optional, to reduce evaporation)

Method

1. Pour equal volumes of hot water into identical beakers.
2. Wrap each beaker in a different insulating material (one beaker is left unwrapped as a control).
3. Record the starting temperature.
4. Record the temperature every minute for a set time (e.g., 20 minutes).
5. Plot cooling curves for each material and compare.

Variables

Variable	Type
Type or thickness of insulation	Independent
Temperature at regular time intervals	Dependent
Volume of water, starting temperature, beaker size, room temperature	Control

Expected Results

• All beakers cool over time, but insulated beakers cool more slowly.
• The best insulator produces the shallowest cooling curve.
• The control (no insulation) cools fastest.

Graph Work

• Plot temperature (y-axis) against time (x-axis) for each material on the same axes.
• The gradient of each curve represents the rate of cooling — steeper = faster cooling = worse insulation.

Common Errors and Improvements

Error	Improvement
Water evaporates, causing extra cooling	Place a lid on each beaker
Insulation not applied consistently	Ensure same thickness and coverage for all beakers
Draughts in the room affect results	Perform the experiment away from windows and doors

Safety

• Handle hot water carefully to avoid burns.
• Use a measuring cylinder rather than pouring directly from a kettle.

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Required Practical 3: Resistance (Effect of Length on Wire)

Topic: Electricity (Paper 1)

Aim

To investigate how the length of a wire affects its resistance.

Equipment

• Constantan or nichrome wire (attached to a ruler)
• Ammeter
• Voltmeter
• Power supply (low voltage)
• Crocodile clips
• Ruler

Method

1. Set up a series circuit with the power supply, ammeter, and a measured length of wire.
2. Connect the voltmeter in parallel across the wire.
3. Measure the current (I) and potential difference (V) for a length of wire (e.g., 10 cm).
4. Calculate resistance: R = V / I.
5. Repeat for different lengths (e.g., 20 cm, 30 cm, ... 100 cm).
6. Repeat each length three times and calculate mean resistance.

Variables

Variable	Type
Length of wire	Independent
Resistance (calculated from V and I)	Dependent
Wire material, wire diameter, temperature, voltage	Control

Expected Results

• Resistance is directly proportional to length.
• A graph of resistance against length should be a straight line through the origin.
• Doubling the length doubles the resistance.

Graph Work

• Plot resistance (y-axis) against length (x-axis).
• Draw a line of best fit — it should pass through the origin.
• The gradient represents the resistance per unit length.

Common Errors and Improvements

Error	Improvement
Wire heats up, changing resistance	Use a low current; switch off between readings; allow cooling time
Crocodile clips not making good contact	Ensure firm, clean connections
Wire not straight against ruler	Tape wire firmly to the ruler

Safety

• The wire may become hot at high currents — do not touch during the experiment.
• Use a low voltage (e.g., 1–2 V) to minimise heating.

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Required Practical 4: I-V Characteristics

Topic: Electricity (Paper 1)

Aim

To investigate the I-V characteristics of a resistor, a filament lamp, and a diode.

Equipment

• Variable resistor (or variable power supply)
• Ammeter
• Voltmeter
• Component to test (resistor, lamp, or diode)
• Power supply
• Switch

Method

1. Set up the circuit with the component in series with the ammeter and variable resistor.
2. Connect the voltmeter in parallel across the component.
3. Vary the resistance (or voltage) to change the current.
4. Record pairs of V and I values.
5. Reverse the power supply connections to obtain negative V and I values.
6. Plot the I-V graph.

Variables

Variable	Type
Potential difference (V) across the component	Independent
Current (I) through the component	Dependent
Temperature (for fair comparison), component type	Control

Expected Results and I-V Graphs

Component	Graph Shape	Explanation
Resistor (ohmic conductor)	Straight line through origin	Resistance is constant; V and I are directly proportional (Ohm's law)
Filament lamp	Curved line (S-shape through origin)	As current increases, the filament heats up, resistance increases, so the line curves
Diode	No current for negative V; current increases rapidly above ~0.7 V in forward direction	Diodes only conduct in one direction above the threshold voltage

graph LR
    A["Ohmic Resistor<br>Straight line through origin"] --- B["Filament Lamp<br>S-curve through origin"]
    B --- C["Diode<br>Only conducts one way"]

Common Errors and Improvements

Error	Improvement
Lamp heats up between readings	Allow the lamp to cool between readings or take readings quickly
Not enough data points	Take at least 6–8 readings in each direction
Diode appears not to work	Check it is connected in the forward direction

Safety

• The filament lamp can become very hot — do not touch it during the experiment.
• Use a low voltage to avoid overheating.

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Required Practical 5: Density

Topic: Particle Model of Matter (Paper 1)

Aim

To measure the density of regular and irregular solid objects and liquids.

Equipment

• Balance
• Ruler (for regular solids)
• Measuring cylinder (for irregular solids and liquids)
• Water
• Eureka (displacement) can (alternative for irregular solids)
• Calculator

Method — Regular Solid

1. Measure the mass using a balance.
2. Measure the dimensions (length, width, height) using a ruler or vernier callipers.
3. Calculate volume: V = l x w x h (for a cuboid) or V = pi x r^2 x h (for a cylinder).
4. Calculate density: rho = m / V.

Method — Irregular Solid

1. Measure the mass using a balance.
2. Fill a measuring cylinder with water and record the initial volume.
3. Gently lower the object into the water.
4. Record the new volume.
5. Volume of object = final volume - initial volume.
6. Calculate density: rho = m / V.

Method — Liquid

1. Place an empty measuring cylinder on a balance and record its mass.
2. Pour a known volume of liquid into the measuring cylinder.
3. Record the mass of the cylinder plus liquid.
4. Mass of liquid = total mass - mass of empty cylinder.
5. Calculate density: rho = m / V.

Variables

Variable	Type
Type of material	Independent
Density (calculated)	Dependent
Measurement method, temperature	Control

Common Errors and Improvements

Error	Improvement
Air bubbles trapped on irregular solid	Tilt the object as you lower it; gently tap the cylinder
Parallax error reading the measuring cylinder	Read at eye level, at the bottom of the meniscus
Inaccurate dimensions for small objects	Use vernier callipers or a micrometer for greater precision

Safety

• Wipe up any water spills immediately to prevent slipping.
• Handle glass measuring cylinders carefully.

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Required Practical 6: Force and Extension (Hooke's Law)

Topic: Forces (Paper 2)

Aim

To investigate the relationship between force and extension of a spring.

Equipment

• Spring
• Clamp stand, boss, and clamp
• Ruler (with mm divisions)
• Slotted masses and mass hanger
• Pointer (attached to the bottom of the spring to aid reading)
• Safety goggles
• Cushion or soft surface beneath the spring

Method

1. Clamp the spring at the top of the stand.
2. Measure and record the natural (unstretched) length of the spring.
3. Add a mass to the spring, wait for it to stop oscillating, and measure the new length.
4. Calculate extension: extension = stretched length - natural length.
5. Repeat, adding masses in equal increments.
6. Plot a graph of force against extension.

Variables

Variable	Type
Force applied (weight of masses)	Independent
Extension of the spring	Dependent
Type of spring, gravitational field strength	Control

Expected Results

• For small extensions, force is directly proportional to extension (Hooke's law: F = k x e).
• The graph is a straight line through the origin up to the limit of proportionality.
• Beyond the limit of proportionality, the line curves — the spring no longer obeys Hooke's law.
• The gradient of the straight-line section equals the spring constant (k).

Graph Work

• Plot force (y-axis) against extension (x-axis).
• The gradient of the linear region = spring constant k (in N/m).
• Identify the limit of proportionality (where the line starts to curve).
• The area under the graph (in the linear region) equals the elastic potential energy stored.