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1.) Consider a parallel plate capacitor with plates of area1.04 m 2 whose plates

ID: 1763001 • Letter: 1

Question

1.) Consider a parallel plate capacitor with plates of area1.04 m2whose plates are 1.30 cm apart. Thegap between the plates is filled with air (assume thatair is unity) and thepositive plate has a charge of 11.4 nC on it while the negative plate has anegative charge of equal magnitude on it.

The capacitor has its plate-spacing reduced to 1.01 mm, and the plates are connected to a1.55 V battery.

The capacitor is disconnected from the battery and the platesare returned to their initial spacing.

The space between the plates is now filled with a fluid with adielectric constant of 4.43.

d) What is the voltage across the capacitor?
4 V

The area of overlap between the capacitor plates is increased to2.31 m2.

f) What is the voltage across the capacitor?
6 V

Explanation / Answer

b) Q = CV           =(oA / d) * V           = ( 8.9 x10-12 * 1.04 / 0.00101 ) * 1.55           = 14.20nC c) V =Qd /Ao          = 14.20 x10-9 * 0.013 / 1.04*8.9x10-12          = 19.94 V