Coulomb's Law

Question 1

Electric Field strength at a point

Answer 1

Electric Field strength at a point is the force per unit charge exerted on a unit positive charge that acts on a stationary charge.

E = F/Q OR V/d

Question 2

What is Coulomb’s law?

Answer 2

Any two point charges exert an electrical force on each other that is proportional to the product of their charges and inversely proportional to the square of the distance between them.

Question 3

Formula for electrical force

Answer 3

F = kQ₁Q₂ / r² & k = 1 / 4πε₀

F = Q₁Q₂ / 4πε₀r²
NB: distance r is always measured from the center

Question 4

Formula for Electric field strength (of a radial field)

Answer 4

E = Q₁ / 4πε₀r²

Question 5

What is electric potential at a point?

Answer 5

This is the work done in bringing a unit positive charge from infinity to that point.

Question 6

Equation of what to done by a positive charge

Answer 6

W = QV

Question 7

Equation for electric potential

Answer 7

V = Q / 4πε₀r

Question 8

How do you calculate the potential at a point caused by more than one charge

Answer 8

Find each potential separately and add them.

NB: the positive charge causes positive potentials and the negative charge causes negative potentials.