OCR · A-Level · Physics
Course version: H556 · Version from Sept 2015
(d) the concept of electric fields as being one of a number of forms of…
Full specification wording
Coulomb’s law: (d) the concept of electric fields as being one of a number of forms of field giving rise to a force.
A field is a region of space in which a suitable object experiences a force.
Checked against the OCR H556 specification (opens in a new tab) on .
- Point 3 of 3
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
A field is a region of space in which a suitable object experiences a force. Electric fields are one of several forms of field, alongside gravitational, magnetic and nuclear fields. An electric field exists around any charged object and exerts a force on any other charge placed in it. The force can be attractive or repulsive, depending on the signs of the charges. The concept of a field allows action at a distance to be described without invoking direct contact. For example, the electric field of a point charge can be represented by radial field lines, and the force on a test charge is given by F = qE. Fields are vector quantities and obey superposition.
What earns the marks
- Defines a field as a region where a force acts on a suitable object.
- Identifies electric fields as one of several forms of field, such as gravitational, magnetic and nuclear.
- States that electric fields arise from electric charge and exert forces on other charges.
- Recognises that electric forces can be attractive or repulsive.
- Uses the concept of a field to explain action at a distance.
Common mistakes and how to put them right
Thinking that a field requires a medium to exist.
Put it right: Electric fields can exist in a vacuum.
Confusing the field with the force.
Put it right: The field is a property of space, while force depends on the object placed in the field.
Assuming that electric field lines can cross.
Put it right: Field lines never cross because the field direction is unique at each point.
Believing that electric fields are always uniform.
Put it right: The field of a point charge is radial and non-uniform.
Exam tips
- Use the definition ‘force per unit positive charge’ when describing electric field strength.
- Link the concept of a field to the force equation F = qE when explaining how a charge experiences a force.
- In multiple-choice questions, distinguish between scalar fields (e.g. temperature) and vector fields (e.g. electric, gravitational).
Try the lesson
The start of the Coulomb’s law: (d) the concept of electric fields as being one of a number of forms of field giving rise to a force. lesson, made from checked teaching notes for this specification point.
Listen
A field is a region of space in which a suitable object experiences a force. Electric fields are one of several forms of field, alongside gravitational, magnetic and nuclear fields. An electric field exists around any charged object and exerts a force on any other charge placed in it. The force can be attractive or repulsive, depending on the signs of the charges. The concept of a field allows action at a distance to be described without invoking direct contact. For example, the electric field of a point charge can be represented by radial field lines, and the force on a test charge is given by F = qE. Fields are vector quantities and obey superposition. A strong answer earns marks for these points. Defines a field as a region where a force acts on a suitable object. Identifies electric fields as one of several forms of field, such as gravitational, magnetic and nuclear. States that electric fields arise from electric charge and exert forces on other charges. Recognises that electric forces can be attractive or repulsive. Exam tip: Use the definition ‘force per unit positive charge’ when describing electric field strength.
See it
Key words
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Field
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Electric field
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Vector nature of fields
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See every definition
- Field
- A region of space in which a suitable object experiences a force.
- Electric field
- One of a number of forms of field giving rise to a force, existing around any charged object and exerting a force on any other charge placed in it.
- Vector nature of fields
- Fields are vector quantities and obey superposition.
Label the diagram
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1Box 1
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3Box 3
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