Written Science Quiz

a 230V a.c. single-phase circuit draws a current of 5A. a wattmeter connected into the circuit indicates 1000W. Calculate the power factor.

A single-phase a.c. motor draws a current of 20A from a 231V, 50Hz supply at a power factor of 0.8 lagging. Calculate the power input to the motor. Answer in Watts

Calculate the power factor for an a.c. circuit having a resistor of 8 ohms connected in series with an inductor having a reactance of 12 ohms.

A coil of inductance 0.1 H and resistor of resistance 40 Ω are connected to a 250 V, 50 Hz supply. Determine the impedance of the circuit.

A 230 V, single phase machine, draws a current of 10 A at a power factor of 0.8. Calculate the power dissipated by the machine. Answer in KW

A load of 1 kW takes a current of 5 A from a 230 V supply. Calculate the power factor.

A lamp emitting 1000 cd in all directions is suspended 2 m above a surface. Calculate the luminance:

Immediately below the lamp. Answer in LUX

A coil of inductance 0.1 H and resistance 40 Ω is connected to a 230 V 50 Hz supply. Determine, showing all calculations, the impedance of the circuit. Answer in ohms

Determine the power factor for a 1 kW load that draws 5 A from a 230V supply

Determine, showing all calculations, the phase current when three resistors, each having a resistance of 15 Ω, are connected in starto a 400 V three-phasesupply. Answer in amps