Question

Electric field due to a source charge Q at the location of test charge qo is E. What is the

electric field due to this source charge if test charge is replaced by -qo ?​

Answer 1

Given info : electric field due to a source charge Q at the location of test charge q₀ is E.

To find : what is the electric field due to this source charge if text charge is replaced by -q₀ ?

solution : first let's understand the definition of electric field.

electric field is the force per unit test charge.

i.e., E = F/q₀

⇒F = q₀E, it is clear by this equation that the electric field and force are in same direction and magnitude of force is q₀ times of electric field.

it means, electric field doesn't depend on sign of test charge because it is just quantity which is used to find electric field.

now if we substitute test charge by -q₀, electric field still remains same. and direction of electric field still remains the same direction (i.e., direction of force).

in short, electric field due to this source charge still remains E. if test charge is -q₀.