Core Practicals Overview

The Edexcel GCSE Physics (1PH0) specification includes 8 core practicals that you must know in detail. Although you carry out these experiments in class, you are assessed on them in the written exam — not through coursework. Questions may ask you to describe the method, identify variables, analyse data, evaluate the procedure, or suggest improvements.

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The 8 Core Practicals at a Glance

CP	Title	Key Equation / Concept	Paper
CP1	Investigating force and extension (Hooke's law)	F = kx	1
CP2	Investigating the effectiveness of different insulating materials	ΔE = mcΔθ (thermal insulation)	1
CP3	Investigating force, mass, and acceleration	F = ma	1
CP4	Investigating specific heat capacity	ΔE = mcΔθ	1
CP5	Investigating I–V characteristics of circuit components	V = IR	1
CP6	Investigating resistance and wire length	R = V / I	1
CP7	Investigating absorption and emission of infrared radiation	Infrared / Leslie cube	1
CP8	Investigating light intensity and distance (inverse square law)	Light intensity ∝ 1/d²	2

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CP1: Force and Extension (Hooke's Law)

Purpose

To investigate the relationship between the force applied to a spring and its extension, and to determine the spring constant.

Key Variables

Variable Type	Variable
Independent	Force applied (weight added)
Dependent	Extension of the spring
Control	Same spring, same measuring technique, same starting position

Brief Method

1. Set up a clamp stand with a spring hanging vertically. Record the original (natural) length of the spring using a ruler with a mm scale.
2. Add a known mass (e.g. 100 g = 0.98 N) to the spring.
3. Measure the new length and calculate the extension (new length − original length).
4. Repeat, adding more masses in equal increments.
5. Plot a graph of force (y-axis) against extension (x-axis).
6. The gradient of the straight-line section = spring constant (k).

What You Need to Know for the Exam

• The straight-line portion of the graph shows the spring obeying Hooke's law (F is directly proportional to x).
• The point where the graph curves is the limit of proportionality — beyond this, the spring no longer obeys Hooke's law.
• Spring constant k = gradient of the straight line = F / x.
• Safety: use eye protection in case the spring snaps; place a cushion below to catch falling masses.

Exam Tip: Extension is NOT the same as length. Extension = new length − original length. A very common error is to plot length instead of extension.

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CP2: Effectiveness of Insulating Materials

Purpose

To investigate which materials are the best thermal insulators by measuring the rate of cooling of hot water wrapped in different materials.

Key Variables

Variable Type	Variable
Independent	Type of insulating material
Dependent	Temperature change (or final temperature after a set time)
Control	Volume and starting temperature of water, thickness of insulation, size of container, same time interval

Brief Method

1. Pour equal volumes of hot water (e.g. 80°C) into identical beakers.
2. Wrap each beaker in a different insulating material (same thickness). Leave one beaker unwrapped as a control.
3. Record the temperature every minute for a set time (e.g. 10 minutes).
4. The material with the smallest temperature drop is the best insulator.

What You Need to Know for the Exam

• A good insulator reduces the rate of thermal energy transfer.
• Control variables are critical — the test is only fair if the only thing that changes is the insulating material.
• Repeats improve reliability.
• A lid on the beaker reduces energy loss by evaporation and convection from the top.

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CP3: Force, Mass, and Acceleration (F = ma)

Purpose

To investigate the relationship between force, mass, and acceleration, and to verify Newton's second law.

Key Variables

Variable Type	Variable
Independent	Force applied (or mass of the trolley)
Dependent	Acceleration
Control	Total mass (when varying force) or force (when varying mass), friction-compensated track

Brief Method

1. Set up a dynamics trolley on a track with a pulley at one end.
2. Attach a string from the trolley, over the pulley, to a hanging mass (which provides the accelerating force).
3. Use light gates or a data logger to measure the acceleration of the trolley.
4. Vary the force by changing the hanging mass (keeping total system mass constant by transferring masses from the trolley to the hanger).
5. Plot a graph of acceleration (y-axis) against force (x-axis) — expect a straight line through the origin.

What You Need to Know for the Exam

• If F ∝ a (with constant mass), the graph is a straight line through the origin.
• The total system mass must stay constant — when you add mass to the hanger, remove the same mass from the trolley.
• Friction compensation: tilt the track slightly so the trolley moves at constant speed when given a gentle push (without the hanging mass).
• a = F / m, so the gradient of the a–F graph = 1/m.

Exam Tip: The most common error in this experiment is forgetting to keep the total system mass constant. If you just add masses to the hanger without removing them from the trolley, the total mass changes and the results are invalid.

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CP4: Specific Heat Capacity

Purpose

To determine the specific heat capacity of a material (e.g. a metal block or water) by measuring the energy input and temperature change.

Key Variables

Variable Type	Variable
Independent	Energy supplied (via a heater)
Dependent	Temperature change
Control	Mass of material, insulation around the block

Brief Method

1. Measure the mass of the metal block (or water).
2. Insert a thermometer and an electric heater into the block.
3. Record the starting temperature.
4. Switch on the heater and use a joulemeter (or calculate E = Pt) to measure the energy supplied.
5. Record the temperature at regular intervals.
6. Use ΔE = mcΔθ rearranged to c = ΔE / (mΔθ) to calculate the specific heat capacity.

What You Need to Know for the Exam

• Insulate the block to reduce energy losses to the surroundings.
• The calculated value of c is often higher than the true value because some energy is lost to the surroundings rather than heating the block.
• Use a thermometer with good resolution (e.g. 0.5°C or better).

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CP5: I–V Characteristics of Circuit Components

Purpose

To investigate how the current through a component varies with the potential difference across it, for a resistor, a filament lamp, and a diode.

Key Variables

Variable Type	Variable
Independent	Potential difference (adjusted using a variable resistor)
Dependent	Current
Control	Same component, same temperature (for the resistor)

Brief Method

1. Set up a circuit with a power supply, variable resistor (or potentiometer), ammeter (in series), and voltmeter (in parallel with the component).
2. Adjust the variable resistor to change the potential difference.
3. Record the current and potential difference at each setting.
4. Reverse the battery connections and repeat for negative values.
5. Plot an I–V graph (current on y-axis, voltage on x-axis).

Expected Results

Component	I–V Graph Shape	Explanation
Resistor (at constant temperature)	Straight line through origin	Current is directly proportional to voltage — constant resistance (Ohm's law)
Filament lamp	Curved (S-shape through origin)	As current increases, the filament heats up, resistance increases
Diode	Almost no current in reverse; sharp increase forward above ~0.6 V	Current only flows in one direction (above the threshold voltage)

Exam Tip: You MUST be able to sketch all three I–V graphs from memory. The resistor is a straight line, the filament lamp is a smooth curve, and the diode shows virtually zero current in reverse and a sharp increase in the forward direction.

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CP6: Resistance and Wire Length

Purpose

To investigate how the resistance of a wire varies with its length.

Key Variables

Variable Type	Variable
Independent	Length of the wire
Dependent	Resistance
Control	Material, diameter (cross-sectional area), temperature of the wire

Brief Method