As shown in fig P and Q are two co-axial conducting loops separated by some distance. When the switch S is closed, a clockwise current I p flows in P(as seen by E), an and induced current IQ 1 flows in Q. The switch remains closed for a long time. When S is opened, a current IQ 2 flows in Q. Then the direction IQ 1 and IQ 2 (as seen by E) are.

respetively anticlockwise and clockwise

respectively clockwise and anticlockwise

JEE Questions for Physics Alternating Current Quiz 6

For high frequency, capacitor offers

0%
more resistance
0%
less resistance
0%
zero resistance
0%
none of these

An inductance L having a resistance R is connected to an alternating source of angular frequency ω. The quality factor (Q) of the inductance is

0%
0%
2)
0%
0%

A uniform but time varying magnetic field B (t) exists in a circular region of radius a and is directed into the plane of the paper as shown. The magnitude of indudced electric field at point P at a distance r from the centre of the circular region is
Physics-Alternating Current-61707.png

0%
zero
0%
decreases as 1 / r
0%
increases as r
0%
decreases as 1/r2

A wind powered generator converts wind energy into electrical energy. Assume that the generator converts a fixed fraction of the wind energy intercepted by its blades into electric energy. For wind speed v, the electric power output will be proportional to

0%
ν
0%
ν2
0%
ν3
0%
ν4

Two circular coils can be arranged in any of the three situations shown in fig. their mutual inductance will be
Physics-Alternating Current-61710.png

0%
maximum in situation (i)
0%
maximum in situation(ii)
0%
maximum in situation (iii)
0%
the same in all situations

The current flowing in a step down transformer 220 V to 22 V having impedance 220Ω is

0%
1A
0%
0.1 A
0%
1 mA
0%
0.1 mA

The power factor of an a.c. circuit having resistance R and inductance L connected in series to an a.c. source of angular frequency ω is

0%
R/ωL
0%
ωL/R
0%
0%
zero

A coil having 500 square loops of side 10cm is placed normal to magnetic field which increases at a rate of 1 T/sec. The induced e.m.f is

0%
0.1 V
0%
0.5 V
0%
1 V
0%
5 V

Power delivered by the source in the circuit is maximum, when

0%
ωL = ωC
0%
ωL = 1/ωC
0%
ωL = ωC2
0%

An inductor L and a capacitor C are connected in the circuit as shown in fig. The frequency of power supply is equal to the resonance frequency of the circuit. Which ammeter will read zero ampere?
Physics-Alternating Current-61718.png

0%
A1
0%
A2
0%
A3
0%
none of these.

A conducting square loop of side L and resistance R moves in its plane with a uniform velocity v perpendicular to one of its sides. A magnetic induction B constant in time and space, pointing perpendicular and into the plane of the loop exists everywhere with part of the loop outside the field, as shown fig. the induced e.m.f is
Physics-Alternating Current-61719.png

0%
B ν R
0%
VBL/R
0%
ν B L
0%
BL ν/2

For the LR circuit shown in fig the phase angle if frequency is 100/π is
Physics-Alternating Current-61721.png

0%
30o
0%
60o
0%
45o
0%
90o

As shown in fig P and Q are two co-axial conducting loops separated by some distance. When the switch S is closed, a clockwise current I_p flows in P(as seen by E), an and induced current IQ₁ flows in Q. The switch remains closed for a long time. When S is opened, a current IQ₂ flows in Q. Then the direction IQ₁ and IQ₂ (as seen by E) are.
Physics-Alternating Current-61723.png

0%
respectively clockwise and anticlockwise
0%
both clockwise
0%
both anticlockwise
0%
respetively anticlockwise and clockwise

A short circuited coil is placed in a time varying magnetic field. Electrical power is dissipated due to the current induced in the coil. If the number of turns were to be quadrupled and the wire radius halved, the electrical power dissipated would be

0%
halved
0%
2)
0%
doubled
0%
quadrupled

Two coils are placed close to each other. The mutual inductance of the pair of coils depends upon

0%
the tates at which currents are changing in the two coils
0%
relative position and orientation of the two coils
0%
the materials of the wires to the coils
0%
the currents in the two coils

when current changes from +2 A to –2 A in 0.05s, an e.m.f of 8 V is induced in a coil the coefficient of self inductance of the coil is

0%
0.2 H
0%
0.4 H
0%
0.8 H
0%
0.1 H

In an oscilating LC circuit, the maximum charge on the capacitor, is Q. The charge on the capacitor, when the energy is stored equally between the electric and magnetic field is

0%
Q/2
0%
2)
0%
0%
Q/3

When an a.c. source of e.m.f. e = E₀ sin (100t) is connected across a circuit, the phase difference between the e.m.f. e and the current i in the circuit is observed to be π/4, as shown in Fig. If the circuit consists only of R-C or R- L or L- C in series, find the relationship between the two elements
Physics-Alternating Current-61730.png

0%
R = 1 KΩ, C = 10 μF
0%
R = 1 KΩ, C = 1 μF
0%
R = 1 kΩ, L = 10 H
0%
R = 1 kΩ, L = 1 H

0%
0%
2)
0%
0%

In RC circuit while charging, the graph of log I versus time is as shown by the dotted line in the adjoining diagram, where I is the current. When the value of resistance is doubled, which of the solid curves best represents the variation of log I versus time?
Physics-Alternating Current-61737.png

0%
P
0%
Q
0%
R
0%
S

A coil of 40 H inductance is connected in series with a resistance of 8 ohm and the combination is joined to the terminals of a 2V battery. The time constant of the circuit is

0%
40s
0%
20s
0%
5s
0%
1/5s

One conducting U tube can slide inside another as shown in Fig maintaining electrical contacts between the tubes. The magnetic field B is perpendicular to the plane of the figure. If each tube moves towards the other at a constant speed V, then the e.m.f induced in the circuit in terms of B, l and V where l is the width of each tube, will be
Physics-Alternating Current-61740.png

0%
2BlV
0%
zero
0%
-BlV
0%
BlV

The phase difference between the alternating current and emf is π/2. Which of the following cannot be the constituent of the circuit ?

0%
L alone
0%
L, C
0%
R, L
0%
C alone

A circuit has a resistance of 12 ohm and an impedance of 15 ohm. The power factor of the circuit will be

0%
0.125
0%
1.25
0%
0.4
0%
0.8

A coil of inductance 300 mH and resistance 2 Ω is connected to a source of voltage 2V. The current reaches half of its steady state value in

0%
0.3s
0%
0.15s
0%
0.1 s
0%
0.05s

An infinitely long cylinder is kept parallel to a uniform magnetic field B directed along positive z-axis. The direction of induced current on the surface of cylinder as seen from the z axis will be

0%
clockwise of the +ve z axis
0%
anticlockwise of the +ve z axis
0%
zero
0%
along the magnetic field

The root mean square value of the alternating current is equal to

0%
Twice the peak value
0%
Half the peak value
0%
1/2 times the peak value
0%
Equal to the peak value

A magnet is made to oscillate with a particular frequency, passing through a coil as shown in Fig. The time variation of the magnitude of e.m.f. generated across the coil during one cycle is
Physics-Alternating Current-61744.png

0%
0%
2)
0%
0%

As shown in Fig a metal rod makes contact and completes the circuit. The circuit is perpendicular to the magnetic field with B = 0.15 T. If the resistance is 3Ω, force needed to move the rod with a constant speed of 2m/s is
Physics-Alternating Current-61749.png

0%
0%
2)
0%
0%

Three indentical coils, A, B and C are placed with their planes parallel to one another. Coils A and C carry currents as shown in Fig. Coils B and C are fixed in position and coil A is moved towards B. Then, current induced in B is in
Physics-Alternating Current-61755.png

0%
clockwise current
0%
anticlockwise current
0%
no current is induced in B
0%
current is induced only when both coils move

A vertical ring of radius r and resistance R falls vertically. It is in contact with two vertical rails which are joined at the top. The rails are without friction and resistance. There is a horizontal uniform magnetic field of magnitude B perpendicular to the plane of the ring and the rails. When the speed of the ring is v, the current in the section PQ is
Physics-Alternating Current-61756.png

0%
zero
0%
2)
0%
0%

The network shown in Fig is part of a complete circuit. If at a certain instant, the current I is 5 A, and is decreasing at a rate 10³A/s, then (V_B-V_A) is
Physics-Alternating Current-61761.png

0%
20 V
0%
15 V
0%
10V
0%
5V

In the circuit shown in Fig switch S is closed at time t = 0. The charge which passes through the battery in one time constant is
Physics-Alternating Current-61763.png

0%
0%
2)
0%
0%

In an L-R circuit connected to a battery, the rate at which energy is stored in the inductor is plotted against time during the growth of current in the circuit. Which of the following best represents the resulting curve?

0%
0%
2)
0%
0%

In the circuit shown in Fig the coil has inductance and resistance. When X is joined to Y, the time constant is τ during growth of current when the steady state is reached, heat is produced in the coil at a rate P. X is now joined to Z.
Physics-Alternating Current-61774.png

0%
The total heat produced in the coil is P τ
0%
The total heat produced in the coil is 1/2 P τ
0%
The total heat produced in the coil is 2 P τ
0%
The data given is not sufficient to reach a conclusion

A conducting rod PQ of length L = 1.0 m is moving with a uniform speed ν = 2.0 m/s in a uniform magnetic field B = 4.0 T directed into the paper. A capacitor of capacity C=10 μF is connected as shown in Fig . Then
Physics-Alternating Current-61776.png

0%
0%
2)
0%
0%
Charge stored in the capacitor increased exponentially with time

Some magnetic flux is changed from a coil of resistance 10 ohm. As a result, an induced current is developed in it, which varies with time as shown in Fig. The magnitude of change in flux through the coil in weber is
Physics-Alternating Current-61781.png

0%
4
0%
8
0%
2
0%
6

Two concentric and coplanar circular coils have radii a and b as shown in Fig. Resistance of the inner coil is R current in the other coil is increased from 0 to i, then the total charge circulating the inner coil is
Physics-Alternating Current-61783.png

0%
0%
2)
0%
0%

The radius of the circular conducting loop shown in Fig is R. Magnetic field is decreasing at a constant rate α. Resistance per unit length of the loop is ρ. Then current in wire AB is (AB is one of the diameters)
Physics-Alternating Current-61789.png

0%
0%
2)
0%
0%
zero

In the circuit shown in Fig the jockey J is being pulled towards right so that the resistance in the circuit is increasing. Its value at some instant is 5Ω. The current in the circuit at this instant will be
Physics-Alternating Current-61794.png

0%
less than 4 A
0%
more than 4 A
0%
may be less than 4 A depending on the value of L
0%
4 A

The power is transmitted from a power house on high voltage ac because

0%
Electric current travels faster at higher volts
0%
It is more economical due to less power wastage
0%
It is difficult to generate power at low voltage
0%
Chances of stealing transmission lines are minimized

The potential difference V and the current iflowing through an instrument in an ac circuit of frequency f are given by V = 5 cosωt volts and I = 2 sin ωt amperes (where w = 2 πf). The power dissipated in the instrument is

0%
Zero
0%
10 W
0%
5 W
0%
2.5 W

If instantaneous current is given by i = 4 cos (ωt + Φ)) amperes, then the r.m.s. value of current is

0%
4 amperes
0%
2)
0%
0%
Zero amperes

A generator produces a voltage that is given by V = 240 sin 120 t, where t is in seconds. The frequency and r.m.s. voltage are

0%
60 Hz and 240 V
0%
19 Hz and 120 V
0%
19 Hz and 170 V
0%
754 Hz and 70 V

If E₀ represents the peak value of the voltage in an ac circuit, the r.m.s. value of the voltage will be

0%
0%
2)
0%
0%

A sinusoidal ac current flows through a resistor of resistance R. If the peak current is I_p, then the power dissipated is

0%
0%
2)
0%
0%

200 V, 50 Hz, ac is applied to a resistor. The instantaneous value of voltage is

0%
0%
2)
0%
0%

The r.m.s. value of an ac of 50 Hz is 10 amp. The time taken by the alternating current in reaching from zero to maximum value and the peak value of current will be