Electromagnetism – Electric Potential

Question 3-4: refer to a thin, nonconducting ring of radius R, as shown below, which has a charge Q uniformly spread out on it.

 photo Screenshots_2014-11-06-17-08-30_zpsa12ff792.png

The electric potential at a point P, which is located on the axis of symmetry a distance x from the center of the ring, is given by

A. Q / (4πɛ0x)
B. Q / [4πɛ0(Rx2)1/2]
C. Qx / [4πɛ0(Rx2)]
D. Qx / [4πɛ0(Rx2)3/2]
E. QR / [4πɛ0(Rx2)]

(GR9677 #03)


Electric Potential, V = kQ/r 
with = 1/4πɛ0

The distance r of P from the charged ring is r2 = Rx2

Q / [4πɛ0(Rx2)1/2]

Answer: B

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