AC Fundamentals

A function that repeats itself after fixed intervals is said to be:

• a phasor

• harmonic

• periodic

• reactive

If v₁ = 30 sin(ωt + 10°) and v₂ = 20 sin(ωt + 50°), which of these statements are true?

• v₁ leads v₂

• v₂ leads v₁

• v₂ lags v₁

• v₁ lags v₂

• v₁ and v₂ are in phase

The imaginary part of impedance is called:

• resistance

• admittance

• susceptance

• conductance

• reactance

The impedance of a capacitor increases with increasing frequency.

• True

• False

Which of the following is not a right way to express the sinusoid  $A\ \cos\omega t$  ?

•  $A\cos\ 2\pi ft$ 

•  $A\ \cos\left(\frac{2\pi t}{T}\right)$  

•  $A\ \cos\omega\left(t-T\right)$  

•  $A\ \sin\left(\omega t=90\right)$  

The power consumed in a pure inductive circuit is (a)  

Which of these frequencies has the shorter period?

• 1 Krad/s

• 1 Khz

If two sinusoids of the same frequency but of different amplitudes and phase angles are subtracted, the resultant is

• Sine wave of same frequency

• Sine wave of half the original frequency

• Sine wave of double the original frequency

• Not a sine wave

Peak factor for a sine wave is (a)   (Note: answer with three decimal place accuracy)

A sine wave has a positive going zero crossing at $0\degree$ and an rms value of 20 V. What is the instantaneous value at  $145\degree$  ?

• 7.32 V

• 16.22 V

• 26.57 V

• 21.66 V