Alternating Current
Practice Questions
MCQ (Single Correct Answer)
1

In domestic electric mains supply, the voltage and the current are

KCET 2025
2

A sinusoidal voltage produced by an AC generator at any instant t is given by an equation $\mathrm{V}=311 \sin 314$ t. The rms value of voltage and frequency are respectively

KCET 2025
3

A series LCR circuit containing an AC source of 100 V has an inductor and a capacitor of reactances $24 \Omega$ and $16 \Omega$ respectively. If a resistance of $6 \Omega$ is connected in series, then the potential difference across the series combination of inductor and capacitor only is

KCET 2025
4

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

KCET 2024
5

In an $L-C-R$ series circuit, the value of only capacitance $C$ is varied. The resulting variation of resonance frequency $f_0$ as a function of $C$ can be represented as

KCET 2024
6

KCET 2024 Physics - Alternating Current Question 12 English

The figure shows variation of $R, X_L$ and $X_C$ with frequency $f$ in a series $L-C-R$ circuit. Then, for what frequency point is the circuit capacitive?

KCET 2024
7

Total impedance of a series $$L$$-$$C$$-$$R$$ circuit varies with angular frequency of the $$\mathrm{AC}$$ source connected to it as shown in the graph. The quality factor $$Q$$ of the series $$L$$-$$C$$-$$R$$ circuit is

KCET 2023 Physics - Alternating Current Question 27 English

KCET 2023
8

In series $$L C R$$ circuit at resonance, the phase difference between voltage and current is

KCET 2023
9

An ideal transformer has a turns ratio of 10. When the primary is connected to $$220 \mathrm{~V}, 50 \mathrm{~Hz}$$ as source, the power output is

KCET 2023
10

In a series $$L C R$$ circuit, $$R=300 \Omega, L=0.9 \mathrm{H}, C=2.0 \mu \mathrm{F}$$ and $$\omega=1000 \mathrm{~rad} / \mathrm{s}$$, then impedance of the circuit is

KCET 2022
11

A series resonant $$\mathrm{AC}$$ circuit contains a capacitance $$10^{-6} \mathrm{~F}$$ and an inductor of $$10^{-4} \mathrm{H}$$. The frequency of electrical oscillations will be

KCET 2022
12

A fully charged capacitor $$C$$ with initial charge $$q_0$$ is connected to a coil of self inductance $$L$$ at $$t=0$$. The time at which the energy is stored equally between the electric and the magnetic field is

KCET 2022
13

An alternating current is given by $$i=i_1 \sin \omega t+i_2 \cos \omega t$$. The rms current is given by

KCET 2022
14

What will be the reading in the voltmeter and ammeter of the circuit shown?

KCET 2021 Physics - Alternating Current Question 20 English

KCET 2021
15

LC-oscillations are similar and analogous to the mechanical oscillations of a block attached to a spring. The electrical equivalent of the force constant of the spring is

KCET 2021
16

In an oscillating $$L C$$-circuit, $$L=3 \mathrm{mH}$$ and $$C=2.7 \mu \mathrm{F}$$. At $$t=0$$, the charge on the capacitor is zero and the current is $$2 \mathrm{~A}$$. The maximum charge that will appear on the capacitor will be

KCET 2021
17

In the given circuit the peak voltage across $$C, L$$ and $$R$$ are $$30 \mathrm{~V}, 110 \mathrm{~V}$$ and $$60 \mathrm{~V}$$, respectively. The rms value of the applied voltage is

KCET 2020 Physics - Alternating Current Question 16 English

KCET 2020
18

The power factor of $$R-L$$ circuit is $$\frac{1}{\sqrt{3}}$$. If the inductive reactance is $$2 \Omega$$. The value of resistance is

KCET 2020
19

In the given circuit, the resonant frequency is

KCET 2020 Physics - Alternating Current Question 17 English

KCET 2020
20

A $$220 \mathrm{~V}$$ AC supply is connected between points $$A$$ and $$B$$ as shown in figure, what will be the potential difference $$V$$ across the capacitor?

KCET 2020 Physics - Alternating Current Question 18 English

KCET 2020
21

The frequency of an alternating current is $$50 \mathrm{~Hz}$$. What is the minimum time taken by current to reach its peak value from rms value?

KCET 2019
22

An inductor of inductance $$L$$ and resistor $$R$$ are joined together in series and connected by a source of frequency $$\omega$$. The power dissipated in the circuit is

KCET 2019
23
Which of the following, represents the variation of inductive reactance $\left(X_L\right)$ with the frequency of voltage sources $(v)$ ?
KCET 2018
24
A 100 W bulb is connected to an AC source of $220 \mathrm{~V}, 50 \mathrm{~Hz}$. Then, the current flowing through the bulb is
KCET 2018
25
In the series $L-C-R$ circuit, the power dissipation is through
KCET 2018
26
In Karnataka, the normal domestic power supply AC is $220 \mathrm{~V}, 50 \mathrm{~Hz}$. Here, 220 V and 50 Hz refer to
KCET 2018
27
A coil of inductive reactance $1 / \sqrt{3} \Omega$ and resistance $1 \Omega$ is connected to a $200 \mathrm{~V}, 50 \mathrm{~Hz}$ AC supply. The time lag between maximum voltage and current is
KCET 2017
28

In the A.C. circuit shown, keeping ' $K$ ' pressed, if an iron rod inserted into the coil, the bulb in the circuit,

KCET 2017 Physics - Alternating Current Question 4 English
KCET 2017
29
The output of a step down transformers is measured to be 48 V when connected to a 12 W bulb. The value of peak current is
KCET 2017