Electric Fields
Learn Electric Fields for GCSE Physics with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. A separate (triple) physics topic: a charged object is surrounded by an electric field that is strongest close to the object and can cause sparking.
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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.
Topic overview
A charged object creates an electric field around it. This is a Triple-only topic.
The field is strongest close to the object and gets weaker with distance. Field lines are drawn to show the field: they point away from a positive charge and towards a negative charge, and their spacing shows the field's strength.
A second charged object placed in the field experiences a force. The force is greater when the objects are closer together, because the field is stronger there. Field lines explain sparking too: as charge builds, the field between the object and earth becomes strong enough to ionise the air.
Revision notes
The field around a charge
A charged object creates an electric field around it.
The field is strongest close to the object and becomes weaker as distance increases. Field lines are closer together where the field is stronger.
Drawing field lines
Field lines point away from a positive charge and towards a negative charge.
For an isolated sphere the lines are radial, spreading outwards evenly. The arrows show the direction of the force that would act on a positive charge placed in the field.
Force in a field
A second charged object placed in the field experiences a non-contact force.
The force is stronger when the objects are closer, because the field is stronger there. This explains attraction and repulsion in terms of fields rather than just charges.
Key points
- A charged object creates an electric field.
- The field is strongest close to the object.
- Field lines point away from a positive charge.
- Field lines point towards a negative charge.
- Closer field lines mean a stronger field.
- A charge in a field experiences a non-contact force.
Worked examples
Example 1
Describe the direction of the electric field lines around a positive charge. [2 marks]
Model answer
The field lines point away from the charge (1 mark), spreading out radially in all directions (1 mark).
Example 2
Explain why the force between two charged objects increases as they are brought closer together. [2 marks]
Model answer
The electric field is stronger closer to a charged object (1 mark), so a charge placed nearer experiences a greater force (1 mark).
Example 3
Explain how electric fields account for sparking. [2 marks]
Model answer
As charge builds up on an object, the electric field between it and an earthed conductor becomes stronger (1 mark). When the field is strong enough it ionises the air, allowing electrons to jump across and produce a spark (1 mark).
Common mistakes
Drawing field lines towards a positive charge.
They point AWAY from positive and TOWARDS negative.
Saying the field is uniform around a sphere.
It weakens with distance, shown by the lines spreading apart.
Forgetting that field strength explains the force.
A stronger field means a greater force on a charge placed in it.
Saying field lines cross.
Field lines never cross, because the field has one direction at each point.
Exam tips
- Learn the direction convention: away from positive, towards negative.
- Use line spacing to describe field strength.
- Explain forces through field strength at that point.
- Remember this is a Triple-only topic.
Key terms
- Electric field
- The region around a charge where a force acts.
- Field line
- A line showing the direction of the field.
- Radial
- Spreading outwards evenly in all directions.
- Ionise
- To knock electrons off atoms, allowing a spark.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.