Electric Fields — A-Level Physics Revision

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What is Electric Fields?

This topic introduces electric fields, which are created by charged objects and exert forces on other charges. It runs parallel to the study of gravitational fields, introducing Coulomb's Law (an inverse square law for the force between point charges), electric field strength, and electric potential. You will learn to analyse both uniform electric fields (between parallel plates) and radial fields (around point charges).

Board notes: Electric fields are a major A-Level topic for all exam boards (AQA, Edexcel, OCR), with strong parallels to the gravitational fields topic. All boards cover Coulomb's Law, field strength, potential, and the motion of charged particles in uniform and radial fields. The comparison between electric and gravitational fields is a common theme.

Worked example

Common mistakes

• 1Confusing the direction of the electric field with the direction of the force on a negative charge. Electric field lines show the direction of the force on a *positive* test charge. The force on a negative charge, like an electron, is in the opposite direction to the field lines.
• 2Mixing up electric potential and electric field strength. Electric field strength is a vector quantity (force per unit charge), whereas electric potential is a scalar quantity (energy per unit charge).
• 3Incorrectly calculating the force in a uniform field. In a uniform field between parallel plates, the electric field strength E is constant, and the force on a charge q is simply F = Eq. The inverse square law does not apply here.

Electric Fields exam questions

Exam-style questions for Electric Fields with mark-scheme style solutions and timing practice. Aligned to AQA, Edexcel and OCR specifications.

Frequently asked questions

• What is an electric field?

  An electric field is a region of space around a charged object where another charged object will experience an electrostatic force. It is a vector field represented by field lines.

• What is electric potential?

  Electric potential at a point is the work done per unit positive charge in bringing a small test charge from infinity to that point. It is a scalar quantity measured in volts (V).