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The work in joules required to cam a 4.0 C charge from a 4.0 V equipotcntial sur

ID: 2308375 • Letter: T

Question

The work in joules required to cam a 4.0 C charge from a 4.0 V equipotcntial surface to a 6.0 V equipotential surface and back again to the 4.0 V surface is: a) 6.0 E-6 b) 3.0 E-5 c) 1.2 E-5 d) 6.0 E-5 e) zero 5. The equipotential surfaces associated with an isolated point charge are: a) vertical planes b) concentric spheres centered at the charge c) radially outward from the charge d) concentric cylinders with the charge on the axis e) horizontal planes 6. A capacitor C "has a charge Q". The actual charts on its plates are respectively (a) Q, 0 (b) Q, Q (c) Q, -Q (d) Q/2, Q/2 (e) Q/2, -Q/2 7. Each plate of capacitor stores a charge of magnitude 2 muC when a 100 V potential difference is applied. The capacitance is: (a) 5 muF (b) 10 muF (c) 20 muF (d) 50 muF (c) 100 pF

Explanation / Answer

4.

the work done is not depending on the path, in this case there is no net chnage in electric potential,

so the work done is zero, that is.

W = qdV = q[0] = 0

option e is correct.

5.

the euipotential surfaces are associated with the concentric sphere centered at the charge.

hence option b is correct.

7.

the capacitance is,

C = Q/V = 2 uC/100 = 0.02 uF = 0.02x10-6 F= 20X10-9 F= 20 nF

THEREFORE, OPTION C IS CORRECT.