In a series L C R circuit the resistance R was replaced by R 2 . Which of the following statements is CORRECT?

The resonant frequency will reduce and the resonance peak will be sharper

The resonant frequency will be unchanged but the resonance peak will be broader

The resonant frequency will be unchanged but the resonance peak will be sharper

The resonant frequency will increase but the resonance peak will still have the same sharpness as before

In a series L C R circuit the resistance R was replaced by R 2 . Which of the following statements is CORRECT?

The resonant frequency will reduce and the resonance peak will be sharper

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)

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In a series $L C R$ circuit the resistance $R$ was replaced by $\frac{R}{2}$ $.$ Which of the following statements is CORRECT?

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Important Questions on Alternating Current

EASY

Physics>Electricity and Magnetism>Alternating Current>Resonance

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

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:

EASY

Physics>Electricity and Magnetism>Alternating Current>Resonance

In a scries

L C R

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

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>Resonance

A series LCR circuit of

R = 5 Ω, L = 20 mH

and

C = 0.5 μ F

is connected across an

AC

supply of

250 V,

having variable frequency. The power dissipated at resonance condition is ________

\times 10^{2} W .

EASY

Physics>Electricity and Magnetism>Alternating Current>Resonance

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?

EASY

Physics>Electricity and Magnetism>Alternating Current>Resonance

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

A transmitting station releases waves of wavelength

960 m

. A capacitor of

2.56 μ F

is used in the resonant circuit. The self-inductance of coil necessary for resonance is

x \times 10^{- 8} H

. Find

x

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>Resonance

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

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?

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>Resonance

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

Question Image

HARD

Physics>Electricity and Magnetism>Alternating Current>Resonance

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

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>Resonance

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 :-

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>Resonance

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