Alternating Current

Question 1

Alternating current

Answer 1

Induced voltage developed between the ends of a coil revolving about an axis in a magnetic field

Question 2

Why is emf called alternating emf

Answer 2

Polarities of induced emf are reversed during half rotation of the coil

Question 3

Periodic time

Answer 3

Time taken by the coil to complete one revolution
Time taken by the current to complete one cycle

T = 2π/ω

Question 4

Frequency

Answer 4

No of cycles completed by an alternating current in one second

Question 5

Why is there no deflection in the galvanometer when ac is passed through it

Answer 5

An alternating current flows in one direction for one half cycle and in the opposite direction for the other half cycle.
Hence, for one complete cycle mean value of alternating current is zero and galvanometer shows no deflection

Question 6

why is capacitor called blocking capacitor in dc

Answer 6

in dc f = 0 , X_C = infinite

within a fraction of a second, the capacitor becomes completely charged so that the potential across the capacitor and battery becomes the same