Edexcel IGCSE Physics Investigation Variables
Practise Edexcel IGCSE Physics investigation variables by identifying what changes, what is measured and what must be controlled in practical methods.
- Syllabus
- Issue 4 (2024)
- Course
- Physics 4PH1
Practise Edexcel IGCSE Physics investigation variables by identifying what changes, what is measured and what must be controlled in practical methods.
A student uses this apparatus to investigate how the efficiency of an electric motor varies with its input voltage.

This is the student's method.
- connect the electric motor to a d.c. power supply and a joulemeter
- attach a 1.0 kg mass to the electric motor using a length of string
- set the voltage of the power supply to 10 V and switch on the power supply
- switch off the power supply when the mass has been lifted through a distance of 50 cm
- record the input energy to the motor from the joulemeter
- calculate the energy transferred to the gravitational store of the mass
- calculate the efficiency of the motor
The student repeats this process, setting the power supply to a different voltage each time.
Give two control variables for the investigation.
1
2
Any two from:
- MP1. mass being lifted
- MP2. height lifted / distance
- MP3. power supply / circuit being used
- MP4. temperature of motor
Accept:
- weight
Ignore:
- same motor