Question

At a distance r1 from a point charge, the magnitude of the electric field created by the charge is 395 N/C. At a distance r2 from the charge, the field has a magnitude of 119 N/C. Find the ratio r2/r1.

Answer 1

Answer:

r₂/r₁ = 1.82

Explanation:

The electric field due to a point charge, has the following expression:

$E =\frac{k*q}{r^{2}}$

For a distance r₁, the magnitude of the electric field is 395 N/C, so we can solve for r₁², as follows:

r₁² = $\frac{k*q}{395 N/C} }$ (1)

For a distance r2, the magnitude of the electric field is 119 N/C, so we can solve for r₂², as follows:

r₂² = $\frac{k*q}{119 N/C} }$

We can find the quotient r₂/r₁, from (1) and (2):

r₂/r₁ =$\sqrt{395/119}$ = 1.82