Match List-I with List-II. List - I List - II (a) ω L > 1 ω C (i) Current is in phase with emf (b) ω L = 1 ω C (ii) Current lags behind the applied emf (c) ω L < 1 ω C (iii) Maximum current occurs (d) Resonant frequency (iv) Current leads the emf Choose the correct answer from the options given below.

(a) - (ii) ; (b) - (i) ; (c) - (iv) ; (d) - (iii)

(a) - (ii) ; (b) - (i) ; (c) - (iii) ; (d) - (iv)

(a) - (iii) ; (b) - (i) ; (c) - (iv); (d) - (ii)

(a) - (iv) ; (b) - (iii) ; (c) - (ii); (d) - (i)

EASY

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Graph showing variation of current with frequency of $A C$ source in a series $L C R$ circuit is,

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Important Questions on Alternating Current

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Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

LCR

series circuit has an inductance of

100 mH,

connected to a

100 μF

capacitor and the resistive load is

120 Ω

, which is connected to an A.C. source of

60 Hz

. The resonant frequency of the circuit is:

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

A parallel plate capacitor in series with a resistance of $100 Ω,$ an inductor of $20 mH$ and an $A C$ voltage source of variable frequency shows resonance at a frequency of $\frac{1250}{π} Hz$ . If this capacitor is charged by a $D C$ voltage source to a voltage $25 V,$ what amount of charge will be stored in each plate of the capacitor?

EASY

Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

In a scries

L C R

resonance circuit, if we change the resistance only, from a lower to higher value :

EASY

Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

The

Q

factor for a damped oscillator is given by the

EASY

Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

The readings of ammeter and voltmeter in the following circuit are respectively

Question Image

EASY

Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

In an

L C R

series circuit (of inductance

L,

capacitance

C

and resistance

R),

the impedance is minimum when the angular frequency of the source is given by

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

Find the peak current and resonant frequency of the following circuit (as shown in figure).

Question Image

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

A series LCR circuit driven by

300 V

at a frequency of

50 Hz

contains a resistance

R = 3 kΩ

, an inductor of inductive reactance

X_{L} = 250 π Ω

and an unknown capacitor. The value of capacitance to maximise the average power should be:

(take π^{2} = 10)

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

A resonant AC circuit contains a capacitor of capacitance

10^{- 6} F

and an inductor of

10^{- 4} H

. The frequency of electrical oscillations will be :-

EASY

Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

In the given circuit, the resonant frequency is

Question Image

HARD

Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

100 Ω

resistance, a

0.1 μ F

capacitor and an inductor are connected in series across a

250 V

supply at variable frequency. Calculate the value of inductance of inductor at which resonance will occur. Given that the resonant frequency is

60 Hz

EASY

Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

Which of the following combinations should be selected for better tuning of an LCR circuit used for communication?

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Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

Match List-I with List-II.

	List - I		List - II
(a)	$ω L > \frac{1}{ω C}$	(i)	Current is in phase with emf
(b)	$ω L = \frac{1}{ω C}$	(ii)	Current lags behind the applied emf
(c)	$ω L < \frac{1}{ω C}$	(iii)	Maximum current occurs
(d)	Resonant frequency	(iv)	Current leads the emf

Choose the correct answer from the options given below.

EASY

Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

A resistance of

10 Ω

is joined to an inductance of

0.5 H

and a capacitance of

20.24 \times 10^{- 6} F

. When the circuit is connected to the mains supply of

200 V

and frequency

50

cycle per second, maximum current flows in the circuit. The value of current is

EASY

Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

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

Question Image

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

In the given circuit, the reading of voltmeters

V_{1}

and

V_{2}

are 300 volt each. The reading of the voltmeter

V_{3}

and ammeter

A

are, respectively.

Question Image

EASY

Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

In an

L - C - R

circuit,

10 Ω

resistance,

0.5 μ F

capacitor and

8 H

inductor are connected in series. Their angular resonance frequency will be

EASY

Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

An alternating current is flowing through a series

L - C - R

circuit. It is found that the current reaches a value of

1 mA

at both

200 Hz

and

800 Hz

frequency. What is the resonance frequency of the circuit?

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

For an RLC circuit driven with voltage of amplitude

v_{m}

and frequency

ω_{0} = \frac{1}{\sqrt{L C}}

the current exhibits resonance. The quality factor,

Q

is given by

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>Resonance in a Series LCR Circuit

Question Image

In the above circuit, $C = \frac{\sqrt{3}}{2} μ F, R_{2} = 20 Ω, L = \frac{\sqrt{3}}{10} H$ and $R_{1} = 10 Ω .$ Current in $L - R_{1}$ path is $I_{1}$ and in $C - R_{2}$ path it is $I_{2} .$ The voltage of AC source is given by, $V = 200 \sqrt{2} \sin (100 t)$ volts. The phase difference between $I_{1}$ and $I_{2}$ is:

Graph showing variation of current with frequency of AC source in a series LCR circuit is,

Important Questions on Alternating Current

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Graph showing variation of current with frequency of $A C$ source in a series $L C R$ circuit is,