The absolute value of the electric potential at a distance of 4 m from a certain point charge is 200 V. What is the absolute value of this potential at a distance of 8 m from the same point charge?

Question

Quizplus · Accepted Answer

The electric potential at a distance r from a point charge q is given by V = kq/r, where k is Coulomb's constant. 
We are given V1 = 200 V at r1 = 4 m. 
Using this, we can find q = V1r1/k = (200 V)(4 m)/k. 
Now, we can find V2 at r2 = 8 m using V2 = kq/r2 = (kV1r1)/(k r2) = V1(r1/r2). 
Substituting in the given values, we get V2 = (200 V)(4 m/8 m) = 100 V. 
Therefore, the absolute value of the potential at 8 m from the point charge is 100 V. 
So, the correct answer is Choice C.

The Absolute Value of the Electric Potential at a Distance