A.C CIRCUIT

How the low power factor (P.F) can be improve in AC circuit?

• By connecting resistance in series.

• By connecting capacitor in series.

• By connecting inductor in series

• By connecting capacitor in parallel

What is the resistance of the inductive coil takes 5 A current across 240V, 50 Hz supply at 0.8 power factor?

• 48 Ohm

• 42.5 Ohm

• 38.4 Ohm

• 26.6 Ohm

Calculate the impedance of the circuit,

R = 5 Ohm, XL = 36 Ohm, XC = 24 Ohm

• 69 Ohm

• 65 Ohm

• 13 Ohm

• 12 Ohm

What is the line voltage in 3 phase system if the phase voltage is 240V ?

• 380 Volt

• 400 Volt

• 415 Volt

• 440 Volt

In which 3 phase system, the artificial neutral is required to measure the phase voltage?

• 3 wire star connected system

• 4 wire star connected system

• 3 wire delta connected system

• 4 wire delta connected system

Calculate the power by two wattmeter (W1 & W2) method, if one of the wattmeter (W2) reading is taken after reversing.

• W1 * 2

• W1 only

• W1 - W2

• W1 + W2

What relationship is illustrated in between the current and voltage?

• Current and voltage are "in phase"

• Current and voltage are in out of phase

• Current lags behind the voltage

• Current leads ahead of the voltage

In which condition resonance will occur in R-L-C series circuit?

• Inductive reactance (XL) is zero

• Inductive reactance (XL) is equal to capacitive reactance (XC).

• Inductive reactance (XL) is greater then capacitive reactance (XC).

• Inductive reactance (XL) is less than capacitive reactance (XC).

Which AC circuit contains the phase relation between voltage (V) and current (I)?

• Pure resistive circuit

• Resistance and inductance circuit

• Resistance and capacitance circuit

• Resistance, inductance and capacitance circuit.

What is the purpose of phase sequence meter?

• To control the speed of 3 phase motor.

• To protect motor against short circuit fault

• To indicate the incorrect phase sequence of 3 phase

• To ensure the correct phase sequence of 3 phase system