If a AC source is used in a circuit, what changes may be observed in the deflection of galvanometer needle? why?
please answer correctly.
Answers
Answer:
Galvanometer only detects the flow of direct current because it's an unidirectional.
But in case of alternating current, it's sinusoidal i.e. For positive half, it travels in a direction and in negative half, it travels in the opposite direction. This cancels each other in a cycle. Hence, no deflection in Galvanometer.
That's why, Galvanometer can only be used for direct current but not for alternating current.
Hope, you get the answer.
Answer:
Galvanometer is a device which detects (not measure) the flow of Direct Current (DC) only. This is because the galvanometer's needle moves in a direction according to the direction of current. This is only possible in the case of DC current. Try switching the wires, you give to galvanometer while measuring DC current, the galvanometer at first shows deflection in one way but when switch the polarity, the galvanometer's needle deflect in a different direction.
In the case of Alternating Current (AC), it is known that the current alternates every time. It means the current is in one direction at a time while the next time, the current will be in alternating direction. Suppose if the frequency of AC current is 50Hertz, the current will alternate positive and negative cycles at the rate of 50 cycles per second. In this case, if you measure with galvanometer, this alternating current cancels the deflection and thats why you are not able to see deflection on AC current.
I do not want you to bore you with the equations.