Question

79) The absolute potential at a distance of 2.0 m from a negative point charge is-100. V. What is the absolute potential 4.0 m away from the same point charge? A) -50. V B) -25. V C) -0.20 kV D) -0.40 kV E)-0.50 kV

Answer 1

Solution:

Potential at a distance "r" from a point charge is given by

$V_r = \frac{kq}{r}$

q = charge

We are given

$V_2 = \frac{kq}{2} = -100$.................1

and

we have to find

$V_4 = \frac{kq}{4}$.............2

dividing equation (2) by equation (1)

$\frac{V_4}{V_2} = \frac{2}{4}$

this implies

$V_4 = \frac{V_2}{2}$

from equation (1) we know $V_2 = -100\ V$

therefore

$V_4 = \frac{-100}{2} = -50 \ V$..................Answer