Question

If 500 J of work are required to carry a charged particle between two points with a potential difference of 40V, the magnitude of the charge on the particle is:
a) 0.040 C
b) 12.5 C
c) 20C
D) cannot be computed unless the path is give
e) none of these

My solution:
I used the equation V=W/q inorder to solve for the charge. I plugged in the numbers to get 40= (500)/X. The answer I got was .08. According to the book the answer is 12.5 C

The potential difference between two points is 100V. If 2 C is transported from one of these points to the other, the magnitude of work done is:
a) 200J
b) 100 J
c) 50J
d) 100 J
e) 2 J

The solution I figured would use the same equation because involves potential difference and charge. When I calculated the answer using V=W/q I came up with the answer I came up with A 200J.

Am I handling these problems right because in the second question my answer was right but not in the first one.

Since 40 = 500/X, then X = 500/40 = 12.5 C

Your math is unique.

QV= energy
Q= 500/40 Coulombs That is not .08C

The second is correct. QV=W

Answer 1

In fact q= W/ V
This is q= 500J/40V
so, q= 12.5J/V or 12.5 Coulombs (C)