A circuit connected to an ac source of emf e = e 0 sin ⁡ 100 t with t in seconds, gives a phase difference of π 4 between the emf e and current i . Which of the following circuits will exhibit this?

R C circuit with R = 1 k Ω and C = 10 μ F

R C circuit with R = 1 k Ω and C = 1 μ F

R L circuit with R = 1 k Ω and L = 1 m H

R L circuit with R = 1 k Ω and L = 10 m H

At time t = 0 , terminal A in the circuit shown in the figure is connected to B by a key and an alternating current I t = I 0 cos ω t , with I 0 = 1 A and ω = 500 rad s - 1 starts flowing in it with the initial direction shown in the figure. At t = 7 π 6 ω , the key is switched from B to D. Now onwards only A and D are connected. A total charge Q flows from the battery to charge the capacitor fully. If C = 20 μ F , R = 10 Ω and the battery is ideal with of 50 V , identify the correct statement(s).

Magnitude of the maximum charge on the capacitor before t = 7 π 6 ω is 1 × 10 - 3 C .

The current in the left part of the circuit just before t = 7 π 6 ω is clockwise.

MEDIUM

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No power loss associated with pure capacitor in ac circuit.

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Important Questions on Alternating Current

EASY

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

The power factor of a pure capacitive circuit is:

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

An alternating voltage of

220 V, 50 H z

frequency is applied across a capacitor of capacitance

2 μF

. The impedance of the circuit is

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

An alternating voltage

e = 200 \sqrt{2} \sin (100 t)

volt is connected to

1 μ F

capacitor through AC ammeter. The reading of ammeter is

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

An alternating voltage

V = V_{0} s i n ω t

is connected to a capacitor of capacity

C

through an A.C. ammeter of zero resistance. The reading of ammeter is

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

A circuit connected to an ac source of emf

e = e_{0} \sin (100 t)

with

t

in seconds, gives a phase difference of

\frac{π}{4}

between the emf

e

and current

i

. Which of the following circuits will exhibit this?

HARD

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

Derive the expression for capacitance of a parallel plate capacitor. If a dielectric medium is placed in between the plates. How is its capacitance affected?

EASY

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

An alternating voltage of

220 V, 50 Hz

frequency is applied across a capacitor of capacitance

2 μF .

The impedance of the circuit is

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

A resistance

R

draws power

P

when connected to an

AC

source. If an inductance is now placed in series with the resistance, such that the impedance of the circuit becomes

Z

, the power drawn will be:

EASY

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

A parallel combination of pure inductor and capacitor is connected across a source of alternating EMF $e$ . The currents flowing through an inductor and capacitor are $i_{L}$ and $i_{C}$ respectively. In this parallel resonant circuit, the condition for currents $i$ $, i_{L}$ and $i_{C}$ is ( $i =$ net RMS current in the circuit)

EASY

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

An alternating voltage

V = 200 \sqrt{2} \sin (100 t) V

is connected to a

1 μ F

capacitor through an AC ammeter. The reading of the ammeter is

EASY

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

An alternating current circuit contains only a capacitor. Draw a circuit diagram and derive current, phase difference and capacitive reactance.

EASY

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

A small signal voltage

V (t) = V_{0} \sin ω t

is applied across an ideal capacitor

C

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

An alternating voltage given as

V = 200 \sqrt{2} \sin 100 t (V)

is applied is applied to a capacitance of

5 μF

. The current reading of the ammeter will be equal to________

mA

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

60 μF

capacitor is connected to a

110 V

60 Hz

a.c. supply. Determine the root-mean-square value of the current in the circuit.

EASY

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

A bird sitting on a single high tension wire does not get electrocuted because

HARD

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

A voltage

V_{PQ} = V_{0} \cos (ωt)

(where,

V_{0}

is a real amplitude) is applied between the points

P

and

Q

in the network shown in the figure. The values of capacitance and inductance are

C = \frac{1}{ω R \sqrt{3}}

and

L = \frac{R \sqrt{3}}{ω}

. Then, the total impedance between

P

and

Q

EASY

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

Out of the following graphs, which graph shows the correct relation (graphical representation) for LC Parallel resonant circuit?

EASY

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

Find the reactance of a capacitor having a capacitance

0.5 μF

100 Hz

HARD

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

At time

t = 0

, terminal

A

in the circuit shown in the figure is connected to

B

by a key and an alternating current

I (t) = I_{0} \cos (ω t)

, with

I_{0} = 1 A

and

ω = 500 rad s^{- 1}

starts flowing in it with the initial direction shown in the figure. At

t = \frac{7 π}{6 ω}

, the key is switched from B to D. Now onwards only A and D are connected. A total charge

Q

flows from the battery to charge the capacitor fully. If

C = 20 μ F, R = 10 Ω

and the battery is ideal with of

50 V

, identify the correct statement(s).
Question Image

MEDIUM

Physics>Electricity and Magnetism>Alternating Current>AC Voltage Applied to a Capacitor

For the LCR circuit, shown here, the current is observed to lead the applied voltage. An additional capacitor

C^{'}

, when joined with the capacitor C present in the circuit, makes the power factor of the circuit unity. The capacitor

C^{'}

, must have been connected in:
Question Image

No power loss associated with pure capacitor in ac circuit.

Important Questions on Alternating Current

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