Foundations of Electrical Engineering Quiz

The power factor of a D.C. circuit is always ___

• Less than unity

• Unity

• Greater than unity

• Zero

The form factor is the ratio of ___

• Peak value to r.m.s. value

• r.m.s. value to average value

• Average value to r.m.s. value

• Average value to Peak value

According to Kirchhoff's voltage law, the algebraic sum of all IR drops and e.m.f. in any closed loop of a network is always ___

• Negative

• Positive

• Determined by battery e.m.f

• Zero

The peak value of a sine wave is 200 V. Its average value is --

• 127.4 V

• 141.4 V

• 282.8 V

• 200V

For a frequency of 200 Hz, the time period will be --

• 0.05 s

• 0.005 s

• 0.0005 s

• 0.5wb

The input of an A.C. circuit having power factor of 0.8 lagging is 40 kVA. The power drawn by the circuit is --

• 12 kW

• 22 kW

• 32 kW

• 64 kW

In a pure inductive circuit --

• the current is in phase with the voltage

• the current lags behind the voltage by 90°

• the current leads the voltage by 90°

• the current can lead or lag by 90°

A single-phase sinusoidal voltage of 120 Vis connected to a 90 n load. Current in the circuit is

• 13.3mA

• 133mA

• 1.33A

• 1.33mA

In a certain three-wire Y-connected generator, the phase voltages are 2 kV. The magnitudes of the line voltages are ___

• 2,000 V

• 6,000 V

• 666 V

• 3,464 V

In a three-phase system, the voltages are separated by ___

• 45°

• 90°

• 120°

• 180°