quiz 3

In the case of an inductor

• (a) voltage lags the current by π/2

• (b) voltage leads the current by π/2

• (c) voltage leads the current by π/3

• (d) voltage leads the current by π/4

In a pure capacitive circuit if the frequency of ac source is doubled, then its capacitive reactance will be

• (a) remains same

• (b) doubled

• (c) halved

• (d) zero

A bulb is connected first with dc and then ac of same voltage then it will shine brightly with

• a.c

• d.c

• Brightness will be in ratio 1/(1.4).

• Equally with both.

Power factor is maximum in an LCR series circuit when

• X_L=X_C

• R=0

• X_L =0

• X_C =0

The value of a given waveform at any instant time is termed as ___________

• Waveform

• Instantaneous value

• Cycle

• Period

If the frequency of the AC voltage across an inductor is doubled, the inductive reactance of that inductor

• increases to 4 times its original value.

• increases to twice its original value.

• decreases to one-half its original value.

• decreases to one-fourth its original value.

The power factor of an RLC circuit is defined as cos ∅ = R/Z, but the phase angle can also be calculated from ________.

• sin ∅ = (XL - XC)/Z

• sin ∅ = (XL - XC)/RZ

• sin ∅ = Z/(XL - XC)

• sin ∅ = RZ/(XL - XC)

Which of the following diagrams is the correct phasor diagram for V_R, V_L and V?

• 
• 
• 
• 

What happens at resonance?

• Current is maximum

• Impedance is maximum

• Resistance is maximum

• Power factor is maximum

The combine opposition of resistor, capacitor and inductor is called

• Reactance

• Resistor

• Impedance

• None