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http://www.webassign.net/userimages/2040W06Figure3.jpg?db=v4net&id=410135 Two co

ID: 1537563 • Letter: H

Question

http://www.webassign.net/userimages/2040W06Figure3.jpg?db=v4net&id=410135

Two coils are placed next to each other as shown in the figure above. Coil A is connected to an AC current source that generates an alternating current of a fixed amplitude Io and the angular frequency . A voltmeter is used to measure the voltage across the coil B, VB. The arrangement is made so that the coil A is fixed in space and coil B can be moved horizontally. Choose all that are correct from the following.

a. At a constant value of the angular frequency , if the coil B is brought closer to the coil A, the value of the mutual inductance will increase.

b. While the coil B is held stationary nearby the coil A if the angular frequency is increased, the maximum value of the mutual inductance will increase.

c. At a constant value of the angular frequency , if the coil B is moved away from the coil A, the maximum value of VB will decrease.

d. Detailed examination of the time varying voltage VB and the time varying current through the coil A will show that at the moment when the voltage VB is the maximum the current through the coil A is zero.

e. While the coil B is held stationary nearby the coil A if the angular frequency is decreased, there will be no change in the maximum value of VB.

Explanation / Answer

a. TRUE : Because mutual inductance depends on the geometry ( the distance between two coils) [At a constant value of the angular frequency , if the coil B is brought closer to the coil A, the value of the mutual inductance will increase.]
b. FALSE : Because mutual inductance depends on the geometry ( not the current) While the coil B is held stationary nearby the coil A if the angular frequency is increased, the maximum value of the mutual inductance will increase.
c. TRUE : Because mutual inductance would decrease as distance between coils increases[ At a constant value of the angular frequency , if the coil B is moved away from the coil A, the maximum value of VB will decrease.]
d. TRUE : BEcause induced voltage has a phase difference of 180 degrees with the source alternating source coil (Detailed examination of the time varying voltage VB and the time varying current through the coil A will show that at the moment when the voltage VB is the maximum the current through the coil A is zero.)
e. FALSE : Maximum voltage depends on rate of flux change whic inturn depends on the angular frequency [While the coil B is held stationary nearby the coil A if the angular frequency is decreased, there will be no change in the maximum value of VB.]