AQA GCSE Physics Foundation (8463), Foundation tier · Electricity › Static electricity
Practise Electric fields. 7 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
A charged object creates an electric field around it, and another charged object in that field experiences a force. You need to draw the field pattern of an isolated charged sphere and use the idea of an electric field to explain non-contact forces and sparking. This is in GCSE Physics only, not Combined Science.
Key facts
A charged object creates an electric field around itself
A second charged object in the field experiences a force
The field is strongest close to the object and weaker further away
Closer together → bigger force
Field lines show the direction of the force on a small positive charge
Isolated sphere: straight radial lines; outwards for positive, inwards for negative
Notes
What an electric field is
A charged object creates an electric field around itself.
The electric field is the region where a second charged object experiences a force.
The field is strongest close to the charged object. The further away from the object, the weaker the field.
So the force between two charged objects gets stronger as the distance between them decreases.
Drawing the field of an isolated charged sphere
diagram
Draw straight field lines going out from the surface of the sphere in all directions, evenly spaced, like the spokes of a wheel (radial lines).
Each line meets the surface at right angles, as if it came from the centre of the sphere. Field lines never cross.
The arrows show the direction of the force on a small positive charge placed in the field.
Positive sphere: arrows point away from the sphere. Negative sphere: arrows point towards the sphere.
The lines are closest together near the sphere, which shows the field is strongest there.
Positive sphere: radial lines, arrows outwards. For a negative sphere the arrows point inwards.
Using fields to explain forces and sparks
Two charged objects are each in the other's electric field, so each experiences a force without touching: a non-contact force.
Moving them closer puts each one in a stronger part of the other's field, so the force increases.
How to answer each type of question
Draw the electric field pattern
2 marksGrade 5
Use a ruler. Draw at least four evenly spaced straight lines starting at the surface of the sphere and pointing radially (as if from the centre).
Add an arrow on every line: away from a positive sphere, towards a negative sphere.
Example. Draw the electric field pattern around an isolated negatively charged sphere.
Show the model answerHide the model answer
At least four straight, evenly spaced lines drawn radially from the surface of the sphere (1). Arrows on the lines pointing towards the sphere (1).
Don’t lose marks
Drawing curved or crossing lines around a single sphere, or forgetting the arrows.
Drawing arrows the wrong way: outwards is for a positive sphere, inwards for a negative sphere.
Saying the field is the same strength everywhere, or strongest far from the object.
Explaining a non-contact force without saying that the second object is in the first object's electric field.
More tips
Memory tricks
The arrows show where a small positive charge would be pushed: away from +, towards −.
An isolated charged sphere looks like the spokes of a bicycle wheel.
Closer field lines = stronger field.
Exam technique
When a question says 'use the idea of an electric field', the words 'electric field' and 'experiences a force' must appear in your answer.
For field drawings, use a ruler and draw at least four evenly spaced lines with arrows.
For sparking, build the chain: large charge → very strong field → air ionised → charge flows → spark.
What each grade needs
What you need to be able to do, from the first marks up to the top grade.
Grade 4
Describe what an electric field isThe region around a charged object where another charged object experiences a force.
Grade 5
Describe how field strength changes with distanceThe field is strongest close to the charged object and weaker further away.
Grade 5
Draw the field of a charged sphereStraight radial lines: arrows point outwards for a positive sphere and inwards for a negative sphere.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
A small, negatively charged plastic sphere hangs from an insulating thread. A positively charged rod is brought near to the sphere but does not touch it. Describe what happens to the sphere.
It moves towards the rod (the thread swings towards the rod).
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy2 marks
(a) An isolated charged sphere has an electric field around it. What happens to the electric field strength as you move further from the sphere? Tick (✓) one box.[1]
It increases.
It decreases.
It stays the same.
(b) What is used to represent an electric field in a diagram?[1]
Show the answer and mark scheme
(a)Answer: It decreases.
(b)Answer: Field lines
field lines
Question 2Medium6 marks
A small, negatively charged plastic sphere hangs from an insulating thread. A positively charged rod is brought near to the sphere but does not touch it.
(a) Describe what happens to the sphere.[1]
(b) Explain, using the idea of an electric field, why the sphere moves even though the rod does not touch it.[2]
(c) The rod is moved closer to the sphere. Describe and explain how the angle between the thread and the vertical changes.[2]
(d) The positively charged rod is replaced by a negatively charged rod. Describe what happens to the sphere.[1]
Show the answer and mark scheme
(a)Answer: It moves towards the rod (the thread swings towards the rod).
it moves / swings towards the rod
(b)Answer: The charged rod creates an electric field around itself; the charged sphere is in this field, so it experiences a (non-contact) force.
the (charged) rod creates an electric field around it
the (charged) sphere is in the field so it experiences a force
(c)Answer: The angle increases, because the electric field is stronger closer to the rod, so the force on the sphere is greater.
the angle increases
the field is stronger closer to the rod so the force (of attraction) on the sphere is greater
(d)Answer: It moves away from the rod (it is repelled).