ECAT (Engineering College Admission): Physics MCQs with Answers

Question 1

The current in an AC circuit is given by I = 10 sin(100t). The frequency is

Accepted Answer

50 / π Hz

Answer

100 / (2π) Hz

Answer

50 Hz

Answer

100 Hz

Question 2

A series LCR circuit has R = 10 ohm, L = 0.1 H, and C = 100 μF. If the frequency of the AC source is 50 Hz, what is the impedance?

Accepted Answer

10 ohm

Answer

17.9 ohm

Answer

14.1 ohm

Answer

20 ohm

Question 3

How many significant figures in 100.0?

Accepted Answer

4

Answer

1

Answer

2

Answer

3

Question 4

What are the dimensions of force?

Accepted Answer

MLT⁻²

Answer

ML²T⁻²

Answer

MLT⁻¹

Answer

ML²T⁻¹

Question 5

A series LCR circuit has R = 10 Ω, L = 0.1 H, and C = 100 μF. The resonance frequency is

Accepted Answer

50 / π Hz

Answer

50 Hz

Answer

100 / π Hz

Answer

100 Hz

Question 6

The current in an AC circuit is given by I = 5 sin(100πt - π / 2). The frequency is

Accepted Answer

50 Hz

Answer

100 Hz

Answer

25 Hz

Answer

200 Hz

Question 7

In a series LCR circuit, the voltage across the resistor is 100 V, across the inductor is 200 V, and across the capacitor is 200 V. The supply voltage is

Accepted Answer

100 V

Answer

200 V

Answer

300 V

Answer

100 √2 V

Question 8

A 50 Hz AC source is connected to a capacitor of capacitance 100 μF. The reactance is

Accepted Answer

31.83 Ω

Answer

31.83 kΩ

Answer

318.3 Ω

Answer

3183 Ω

Question 9

The quality factor of a series LCR circuit is given by

Accepted Answer

ωL / R

Answer

R / (ωL)

Answer

1 / (ωCR)

Answer

ωCR

Question 10

In an AC circuit, the voltage and current are in phase. The circuit has

Accepted Answer

only resistance

Answer

only inductance

Answer

only capacitance

Answer

resistance and inductance

Question 11

The rms value of an AC is 5 A. The peak value is

Accepted Answer

7.07 A

Answer

5 A

Answer

5 √2 A

Answer

3.535 A

Question 12

A coil has an inductance of 0.1 H and resistance of 10 Ω. It is connected to an AC source of 100 V, 50 Hz. The impedance is

Accepted Answer

33.3 Ω

Answer

10 Ω

Answer

31.4 Ω

Answer

32.4 Ω

Question 13

In a series LCR circuit, the voltage across the inductor is 100 V, across the capacitor is 100 V, and across the resistor is 50 V. The supply voltage is

Accepted Answer

50 √2 V

Answer

50 V

Answer

100 V

Answer

150 V

Question 14

In an LCR circuit, the resonance frequency is 1000 Hz. The capacitance is 100 μF. The inductance is

Accepted Answer

0.25 mH

Answer

0.025 H

Answer

0.25 H

Answer

0.025 mH

Question 15

The power factor of a series LCR circuit at resonance is

Accepted Answer

1

Answer

0

Answer

0.5

Answer

0.707