OCR · GCSE · Physics
Course version: J249 · Version from Sept 2018
Explain the concept of an electric field and how it helps to explain the…
Full specification wording
Static and charge: explain the concept of an electric field and how it helps to explain the phenomena of static electricity (to include: how electric fields relate to the forces of attraction and repulsion) (content found only in the physics separate science qualification)
An electric field is a region in which a charged object experiences a force.
Checked against the OCR J249 specification (opens in a new tab) on .
- Point 5 of 8
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
An electric field is a region in which a charged object experiences a force. The field is represented by field lines whose direction shows the force on a positive charge, and the spacing of the lines shows the strength of the field: closer lines mean a stronger field. Around an isolated positive charge the lines point radially outwards; around an isolated negative charge they point radially inwards. Between two like charges the field lines push apart, giving repulsion; between two opposite charges the lines run from the positive to the negative charge, giving attraction. Static phenomena such as a charged rod attracting small neutral scraps of paper are explained by the field: the field of the charged object polarises the neutral object, and the resulting force acts without the objects touching. This content is assessed only in the physics separate science qualification.
What earns the marks
- Defines an electric field as a region in which a charged object experiences a force.
- States that electric field lines show the direction of the force on a positive charge and that closer lines indicate a stronger field.
- Explains that like charges repel and opposite charges attract because of the forces described by their electric fields.
- Uses the electric field of a charged object to explain how it attracts a neutral object through induced charge separation without contact.
Common mistakes and how to put them right
Describes the electric field as a substance or as 'electricity in the air'.
Put it right by defining it as a region where a charge experiences a force.
Says field lines point towards a positive charge.
Put it right by stating that field lines point away from a positive charge and towards a negative charge.
Claims that a charged object must touch a neutral object to attract it.
Put it right by explaining that the field acts at a distance and polarises the neutral object.
Exam tips
- Define the field in terms of the force on a charge before describing the pattern of field lines.
- Link the direction of field lines to the force on a positive charge so attraction and repulsion follow logically.
- Use the field idea to explain a named static effect, such as a charged rod attracting small neutral scraps, rather than leaving the field abstract.
Try the lesson
The start of the Static and charge: explain the concept of an electric field and how it helps to explain the phenomena of static electricity (to include: how electric fields relate to the forces of attraction and repulsion) (content found only in the physics separate science qualification) lesson, made from checked teaching notes for this specification point.
Have a go first
What is an electric field?
Listen
An electric field is a region in which a charged object experiences a force. The field is represented by field lines whose direction shows the force on a positive charge, and the spacing of the lines shows the strength of the field: closer lines mean a stronger field. Around an isolated positive charge the lines point radially outwards; around an isolated negative charge they point radially inwards. Between two like charges the field lines push apart, giving repulsion; between two opposite charges the lines run from the positive to the negative charge, giving attraction. Static phenomena such as a charged rod attracting small neutral scraps of paper are explained by the field: the field of the charged object polarises the neutral object, and the resulting force acts without the objects touching. This content is assessed only in the physics separate science qualification. A strong answer earns marks for these points. Defines an electric field as a region in which a charged object experiences a force. States that electric field lines show the direction of the force on a positive charge and that closer lines indicate a stronger field. Explains that like charges repel and opposite charges attract because of the forces described by their electric fields. Uses the electric field of a charged object to explain how it attracts a neutral object through induced charge separation without contact. A common slip: Describes the electric field as a substance or as 'electricity in the air'. Instead, defining it as a region where a charge experiences a force. Exam tip: Define the field in terms of the force on a charge before describing the pattern of field lines.
Key words
Say what each word means before you turn the card.
Electric field
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Field lines
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Attraction and repulsion
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Polarises
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See every definition
- Electric field
- A region in which a charged object experiences a force.
- Field lines
- Lines representing a field, whose direction shows the force on a positive charge and whose spacing shows the strength of the field.
- Attraction and repulsion
- Between two like charges the field lines push apart, giving repulsion; between two opposite charges the lines run from the positive to the negative charge, giving attraction.
- Polarises
- The field of a charged object polarises a neutral object, and the resulting force acts without the objects touching.
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