# Apparent Power is MCQ

By Varadi Hema|Updated : July 29th, 2022

The apparent power combines active and reactive power consumed in the circuit. If P is the active or true power consumed by the circuit, Q is the reactive power consumed in the circuit, then apparent power or complex power S is given by; the apparent power is the combination of active and reactive power consumed in the circuit. If P is the active or true power consumed by the circuit, Q is the reactive power consumed in the circuit, then apparent power or complex power S is given by,

S=P+jQ

Here, S=VI

P=VIcos∅=Scos∅

Q=VIsin∅=Ssin∅

S=√(P2+Q2)

Here we will go through a few basic MCQs based on apparent power; these may help us understand the concept of Apparent power.

## Apparent Power MCQ1

The units of the apparent power are

1. Watts
2. VAR
3. VA
4. None

Explanation:

The apparent power can be expressed in VA(Volt-ampere), the active power(P) can be expressed in watts, whereas reactive power can be expressed in VAR (Volt-ampere reactive).

Hence option C is the correct answer.

## Apparent Power MCQ2

A source Vs=200cosωt delivers power to the load at 0.8 power factor lagging. The reactive power is 300 VAR. The apparent power supplied by the source is_______.

1. 500 VA
2. 400 VA
3. 250 VA
4. 600 VA

Solution:

Given that,

Reactive power (Q) = 300 VAR

Power factor cos ∅ =0.8⇒∅=36.860

Q=Ssin∅ =300

S(0.6)=300

S=500 VA

Hence option A is the correct answer.

## Apparent Power MCQ3

Three-loads are connected in parallel across a single-phase, 1200 V, 50 Hz supply.

What is the total complex power of the circuit?

1. (60+j80) kVA
2. (10+j80) kVA
3. (10-j160) kVA
4. (60+j160) kVA

Solution:

Given,

For load1 which is a capacitive load, P1=10 kW , Q1=-40 kVAR

S1=P1+jQ1=10-j40 kVA

For load2, P2=35 kW , Q2=120 kVAR

S2=P2+jQ2=35+j120 kVA

For load3, P3=15 kW, Q3=0 kVAR

S3=P3+jQ3=15 kVA

Total complex power in the circuit is,

S=S1+S2+S3=10-j40+35+j120+15+j0=60+j80 kVA

Hence option A is the correct answer.

## Apparent Power MCQ4

A 230 V source supplies power to two loads connected in parallel. One load draws 10 kW at 0.8 power factor leading, and the second load draws 10 kVA at 0.8 power factor lagging. The complex power delivered by the source is

1. (18+j1.5) kVA
2. (18-j1.5) kVA
3. (20+j1.5) kVA
4. (20-j1.5) kVA

Solution:

P1=S1cos∅1=10

S1(0.8)=10

S1=12.5 kVA

S1=√(P12+Q12)⇒Q1=√(S12-P12)=7.5 kVAR

S2=10 kVA,cos ∅2=0.8  lagging

P2=S2cos ∅2=8 kW

Q2=S2sin ∅2=6 kVAR

S2=8+j6 kVA

Total complex power in the circuit is,

S=S1+S2=10-j7.5+8+j6=18-j1.5 kVA

Hence option B is the correct answer.

## Apparent Power MCQ5

A voltage source of 100 V is applied to an impedance Z=(3+j4). What are the values of active power, reactive power, and apparent power respectively?

1. 1200 W, 1200 VAR and 2200 VA
2. 1600 W, 1600 VAR, and 2000 VA
3. 1200 W, 1600 VAR, and 2000 VA
4. 1600 W, 1200 VAR, and 2200 VA

Answer: C.1200 W, 1600 VAR, and 2000 VA

Solution:

Given that,

Z=(3+j4)

⇒∅=tan-1(4/3)=53.060

V=100 V

I=V/Z=100/√(32+42)=20 A

S=VI=200*10=2000 VA

P=VIcos ∅ =2000(0.6)=1200 W

Q=VIsin ∅ =2000(0.8)=1600 VAR

Hence option C is the correct answer.

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