Electric field — Science definition
The region around a charge where another charge would feel a force; its strength is the force per unit charge, E = F/q, in N/C.
Where it is taught
- Electric Charge & Fields — Electricity, Magnetism & Circuits, Physics & Environmental Science, Grade 12
In use
An electric field describes local force per sufficiently small positive test charge, E=F/q, in N/C.
Electric Charge & Fields
Questions using electric field
Problem 1
A charge of 2 μC (2 × 10⁻⁶ C) sits at a point where it feels an electric force of 0.1 N. Find the electric field strength there.
Answer and explanation
50000 N/C
E = F ÷ q = 0.1 ÷ (2 × 10⁻⁶) = 50,000 N/C.
Problem 2
A charge of 5 μC (5 × 10⁻⁶ C) feels a force of 0.2 N at a point. Find the electric field strength there.
Answer and explanation
40000 N/C
E = F ÷ q = 0.2 ÷ (5 × 10⁻⁶) = 40,000 N/C.
Problem 3
What is an electric field, and how is the direction of the field at a point defined?
Answer and explanation
An electric field is the region around a charge where another charge would feel a force; its strength is the force per unit charge, E = F/q. By convention, the direction of the field at a point is the direction of the force it would exert on a small positive test charge — so field lines point away from positive charges and toward negative charges.