Question

The electric field at the distance of 3.5 meters from an infinite wall of charges is 125 N/C. What is the magnitude of the electric field 1.5 meters from the wall?

Answer 1

Explanation:

It is given that,

Distance, r = 3.5 m

Electric field due to an infinite wall of charges, E = 125 N/C

We need to find the electric field 1.5 meters from the wall, r' = 1.5 m. Let it is equal to E'. For an infinite wall of charge the electric field is given by :

$E=\dfrac{\lambda}{2\pi \epsilon_o r}$

It is clear that the electric field is inversely proportional to the distance. So,

$\dfrac{E}{E'}=\dfrac{r'}{r}$

$E'=\dfrac{Er}{r'}$

$E'=\dfrac{125\times 3.5}{1.5}$  

E' = 291.67 N/C

So, the magnitude of the electric field 1.5 meters from the wall is 291.67 N/C. Hence, this is the required solution.