Seneca
Sign up

Electric Field Strength

Physics: AQA A Level, topic 7.3.2

Electric field strength

Electric field strength is a way of displaying how the force from an object will act at a point far away, without any apparent connection.

Electric field strength

Electric field strength

  • The electric field strength is the force per unit charge felt by an object.
  • E=FQE=\frac{F}{Q}
  • Using Coulomb's law we can find EE
  • F=14πϵ0×Q1Q2r2F=\frac{1}{4{\pi}{{\epsilon}_0}}{\times}\frac{{Q_1}{Q_2}}{r^2}
  • E=14πϵ0×Qr2E=\frac{1}{4{\pi}{{\epsilon}_0}}{\times}\frac{Q}{r^2}
Field concepts

Field concepts

  • The field is the force experienced if we placed a positive point charge at a point.
  • The field will act in the same direction as the force, so if we are looking at the field from a positive charge the force and field will point away.
  • If we are looking at the field from a negative charge the field and the force will point towards the charge.

Radial Field Strength

The field from a charge is the force per unit charge. Field lines show the direction of motion of a positively charged particle.

Direction of the field

Direction of the field

  • From a positive charge, the field lines go radially outwards
  • From a negative charge, the field lines go radially inwards (towards the charge)
Position of the field

Position of the field

  • Radially outward means in straight lines from the centre, like spokes on a wheel.
  • The field lines from a charge are radial lines from the centre.

Test yourself on Electric Field Strength

  • What is the correct equation for electric field strength?

  • What is the electric field strength?

  • What is a radial line from a charge?

  • What direction do the field lines from a positive charge go?

Practise this topic for free