Question 1

What is the difference between electric field strength and electric potential?

Accepted Answer

Electric field strength (E) is a vector quantity, representing the force per unit charge. Electric potential (V) is a scalar quantity, representing the work done per unit charge (energy per charge). E tells you the force a charge experiences, while V tells you the potential energy a charge would have at that point.

Question 2

Why does electric field strength follow an inverse square law, but electric potential follows an inverse law?

Accepted Answer

Electric field strength is derived from Coulomb's Law, which states force is inversely proportional to $r^2$. Since $E = F/q$, E also follows $1/r^2$. Electric potential (V) is derived from the work done, which involves integrating the force over distance. This integration reduces the power of $r$ by one, resulting in V being inversely proportional to $r$ ($V \propto 1/r$).

Question 3

Can electric potential be negative?

Accepted Answer

Yes! Electric potential can be negative if the source charge creating the field is negative. A negative potential means that positive work would be done *by* the field (or negative work *against* the field) to bring a positive test charge from infinity to that point.

Question 4

What is the Principle of Superposition?

Accepted Answer

It states that the net electric field (or potential) at a point due to multiple charges is the sum of the fields (or potentials) from each individual charge. For fields, this is a vector sum, requiring you to consider direction. For potential, it's a simple scalar (algebraic) sum.

Electric field of a point charge

What you need to know

Electric field of a point charge