Question

Find the true statement.

(a) Length of the phasor must be greater than the peak value of alternating voltage or alternating current

(b) When the current reaches its maximum value after emf becomes maximum, then the current is considered to be leading ahead of emf

(c) When the emf reaches its maximum value after current becomes maximum, then the emf is considered to be behind the current

(d) Phasors for voltage and current are in the same direction when the phase angle between voltage and current is zero

I had been asked this question during an interview.

I need to ask this question from Representation of AC Current and Voltage by Rotating Vectors topic in section Alternating Current of Physics – Class 12

Answer 1

The correct choice is (d) Phasors for voltage and current are in the same direction when the phase angle between voltage and current is zero

The best I can explain: The phasors for voltage and current are in the same direction at all times when the phase angle between voltage and current is zero. All the other statements are not valid. Length of the phasor must be equal to the peak value of alternating voltage or alternating current. Also, when the current reaches its maximum value after emf becomes maximum, then the current is considered to be lagging behind the emf and when the emf reaches its maximum value after current becomes maximum, then the emf is considered to lead the current.