Download Aptitude Crack
img not found img not found

Alternating Current and Voltage - Engineering

Q1:

Sine wave A has a positive-going zero crossing at 45°. Sine wave B has a positive-going zero crossing at 60°. Which of the following statements is true?

A Wave A leads wave B by 15°.

B Wave A lags wave B by 15°.

C Wave A leads wave B by 105°.

D Wave A lags wave B by 105°.

ANS:A - Wave A leads wave B by 15°.

Get the power factor of both waves.
Wave A = 45 degrees.
Wave B = 60 degrees.

P.F. (Wave A) = cos (45) = 0.707.
P.F (Wave B) = cos (60) = 0.5.

The implication of this is that Wave A is already at the peak, while Wave B is about the get the peak. Thus, Wave A is leading Wave B by 15 degrees.