Question

If the field strength is e = 9 v/m a distance of 1 m from the charge, what is the field strength e a distance of 3 m from the charge?

Answer 1

The field strength is directly proportional to the square of the distance. Therefore, we can use the relation:
e1 d1² = e2 d2²
where
e1 = 9 v/m
d1 = 1 m
d2 = 3 m
Substituting
9 (1)² = e2 (3²)
e2 = 1 v/m

Answer 2

The field strength is 1 V/m.

Explanation:

Given : If the field strength is E = 9 V/m a distance of 1 m from the charge.

To find : What is the field strength E a distance of 3 m from the charge?

Solution :

The formula of Electric field strength is

`E=(kq)/(r^2)`

where, E=9 V/m is electric field strength

q is the charge

r=1 m is the distance

Substitute the value in the formula,

`9=(kq)/(1^2)`

`9 Vm=kq`

Now, to find field strength a distance of 3 m from the charge

i.e. kq=9 Vm and r=3

Substitute the value in the formula,

`E=(9)/(3^2)`

`E=(9)/(9)`

`E=1\ V/m`

The field strength is 1 V/m.