Alternating Current Test

Question 1
1 / -0

If the rms current in a 50 Hz AC circuit is 5 A, the value of the current \(1\over300\)s after its value becomes zero is

A
\(5\sqrt2A\)

B
\({5\sqrt3\over\sqrt2}A\)

C
\({5\over6}A\)

D
\({5\over\sqrt2}A\)

Question 2
1 / -0

An alternating current generator has an internal resistance \(R_g\) and an internal reactance \(X_g\). It is used to supply power to a passive load consisting of a resistance \(R_g\) and a reactance \(X_L\). For maximum power to be delivered from the generator to the load, the value of \(X_L\) is equal to

A
\(Zero\)

B
\(X_g\)

C
\(-X_g\)

D
\(R_g\)

Question 3
1 / -0

When a voltage measuring device is connected to AC mains, the meter shows the steady input voltage of 220 V. This means

A
Input voltage cannot be AC voltage, but a DC voltage

B
Maximum input voltage is 220 V

C
The meter reads not v but < \(v^2\) > and is calibrated to read \(\sqrt{<v^2>}\)

D
The pointer of the meter is stuck by some mechanical defect

Question 4
1 / -0

To reduce the resonant frequency in an L-C-R series circuit with a generator

A
The generator frequency should be reduced

B
Another capacitor should be added in parallel to the first

C
The iron core of the inductor should be removed

D
Dielectric in the capacitor should be removed

Question 5
1 / -0

Which of the following combinations should be selected for better tuning of an L-C-R circuit used for communication?

A
\(R = 20 \Omega, L =1.5 H, C = 35\mu F\)

B
\(R = 25 \Omega, L =2.5 H, C = 45\mu F\)

C
\(R = 15 \Omega, L =3.5 H, C = 30\mu F\)

D
\(R = 25 \Omega, L =1.5 H, C = 45\mu F\)

Question 6
1 / -0

An inductor of reactance 1\(\Omega\) and a resistor of 2\(\Omega\) are connected in series to the terminals of a 6V (rms) AC source. The power dissipated in the circuit is

A
8 W

B
12 W

C
14.4 W

D
18 W

Question 7
1 / -0

The output of a step-down transformer is measured to be 24 V when connected to a 12 W light bulb. The value of the peak current is

A
\({1\over \sqrt2}A\)

B
\(\sqrt2 A\)

C
\(2A\)

D
\(2\sqrt2A\)

Question 8
1 / -0

In an alternating current circuit consisting of elements in series, the current increases on increasing the frequency of supply. Which of the following elements are likely to constitute the circuit?

(a) Only resistor

(b) Resistor and an inductor

(c) Resistor and a capacitor

(d) Only a capacitor

A
(a),(b)

B
(b),(c)

C
(c),(d)

D
(d),(a)

Question 9
1 / -0

Electrical energy is transmitted over large distances at high alternating voltages. Which of the following statements is (are) correct?

(a) For a given power level, there is a lower current

(b) Lower current implies less power loss

(c) Transmission lines can be made thinner

(d) It is easy to reduce the voltage at the receiving end using step-down transformers

A
(a),(b),(c)

B
(a),(b),(d)

C
(b),(c),(d)

D
(a),(c),(d)

Question 10
1 / -0

For a L-C-R circuit, the power transferred from the driving source to the driven oscillator is \(P=I^2Zcos\phi\)

(a) Here, the power factor \(cos\phi \geq 0, P\geq0\)

(b) The driving force can give no energy to the oscillator (P = 0) in some cases

(c) The driving force cannot syphon out (P < 0) the energy out of oscillator

(d) The driving force can take away energy out of the oscillator

A
(a),(b),(c)

B
(a),(b),(d)

C
(a),(c),(d)

D
(b),(c),(d)

Question 11
1 / -0

The line that draws power supply to your house from street has

(a) zero average current

(b) 220 V average voltage

(c) voltage and current out of phase by 90°

(d) voltage and current possibly differing in phase \(\phi\) such that |\(\phi\)| < \(\pi\over2\)

A
(a),(b)

B
(a),(d)

C
(b),(c)

D
(b),(d)

Submit Test

Alternating Cur...

Question 1

\(5\sqrt2A\)

\({5\sqrt3\over\sqrt2}A\)

\({5\over6}A\)

\({5\over\sqrt2}A\)

Question 2

\(Zero\)

\(X_g\)

\(-X_g\)

\(R_g\)

Question 3

Input voltage cannot be AC voltage, but a DC voltage

Maximum input voltage is 220 V

The meter reads not v but < \(v^2\) > and is calibrated to read \(\sqrt{<v^2>}\)

The pointer of the meter is stuck by some mechanical defect

Question 4

The generator frequency should be reduced

Another capacitor should be added in parallel to the first

The iron core of the inductor should be removed

Dielectric in the capacitor should be removed

Question 5

\(R = 20 \Omega, L =1.5 H, C = 35\mu F\)

\(R = 25 \Omega, L =2.5 H, C = 45\mu F\)

\(R = 15 \Omega, L =3.5 H, C = 30\mu F\)

\(R = 25 \Omega, L =1.5 H, C = 45\mu F\)

Question 6

8 W

12 W

14.4 W

18 W

Question 7

\({1\over \sqrt2}A\)

\(\sqrt2 A\)

\(2A\)

\(2\sqrt2A\)

Question 8

(a),(b)

(b),(c)

(c),(d)

(d),(a)

Question 9

(a),(b),(c)

(a),(b),(d)

(b),(c),(d)

(a),(c),(d)

Question 10

(a),(b),(c)

(a),(b),(d)

(a),(c),(d)

(b),(c),(d)

Question 11

(a),(b)

(a),(d)

(b),(c)

(b),(d)

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Question Analysis

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