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When a bar magnet falls through a long hollow metal cylinder fixed with its axis vertical, the final acceleration of the magnet is

a) equal to zero b) less than g c) Equal to g d) Equal to g in the beginning and then more than g Answer: a) equal to zero... View Article

The direction of induced e.m.f. during electromagnetic induction is given by

a)Faraday's law b) Lenz's law c) Maxwell's law d) Ampere's law Answer: b) Lenz's law Solution: Lenz's law of electromagnetic... View Article

Three solenoid coils of the same dimension, the same number of turns and the same number of layers of winding are taken. Coil 1 with inductance L₁ was wound using a Mn wire of resistance 11 Ωm^-1, coil 2 with inductance L₂ was wound using a similar wire but the direction of winding was reversed in each layer, coil 3 with inductance L₃ was wound using a superconducting wire. The self-inductance of the coils L₁, L₂ and L₃ are

a) L1 = L2 = L3 b) L1 = L2, L3 = 0 c) L1 = L3, L2 = 0 d) L1>L2>L3 Answer: b) L1 = L2, L3 = 0 Solution: Φ =... View Article

The magnetic flux across a loop of resistance 10 Ω is given by ɸ = 5t² – 4t + 1 weber. How much current is induced in the loop after 0.2 sec?

a) 0.4 A b) 0.2 A c) 0.04 A d) 0.02 A Answer: b) 0.2 A Solution: Given, ɸ = 5t2 – 4t + 1 Emf, e = - dɸ/dt = 10t -... View Article

A coil has an area of 0.05 m² & it has 800 turns. It is placed perpendicularly in a magnetic field of strength, 4 x 10^–5 Wb/m^–2. It is rotated through 90⁰ in 0.1 sec. The average emf induced in the coil is

a) 0.056 V b) 0.046 V c) 0.026 V d) 0.016 V Answer: d) 0.016 V Solution: Area, A = 0.05 m2 N = 800 turns Magnetic field... View Article

In a series resonant LCR circuit, the voltage across R is 100 V and R= 1kΩ with C = 2μF. The resonant frequency ω is 200 rad/s. At resonance the voltage across L is.

a) 40 V b) 250 V c) 4 x 10-3 V d) 2.5 x 10-2 V Answer: b) 250 V Solution:' I = V/R = 100/1000 = 0.1 A At resonance,... View Article

A circular loop of radius R carrying current I lies in the X – Y plane with its centre at the origin. The total magnetic flux through the x – y plane is…..

a) Directly proportional to I b) Directly proportional to R c) Directly proportional to R2 d) zero Answer: d) zero... View Article

When a train travels with a speed of 360 km h^–1 along the track separated by 1 meter. The vertical component of the earth’s magnetic field is 0.1 × 10^–4 T. What is the value of induced emf between the rails?

a) 10-2 V b) 10-4 V c) 10-3 V d) 1 V Answer: c) 10-3 V Solution: Velocity of the train = 360 km/h = 360 x (5/18) = 100... View Article

A transformer of efficiency 90% draws an input power of 4 kW. An electrical appliance connected across the secondary draws a current of 6 A. The impedance of the device is………

a) 60 Ω b) 50 Ω c) 80 Ω d) 100 Ω Answer: d) 100 Ω Solution: Impedance, η = 90/100 = 0.9 ... View Article

A circular coil of diameter 21 cm is placed in a magnetic field of induction 10^-4 T. The magnitude of flux linked with the coil, when the plane of coil makes an angle 30° with the field is

a) 1.44 x 10-6 Wb b) 1.732 x 10-6 Wb c) 3.1 x 10-6 Wb d) 4.2 x 10-6 Wb Answer: b) 1.732... View Article

When a circular coil of radius 1 m and 100 turns is rotated in a horizontal uniform magnetic field, the peak value of emf induced is 100 V. The coil is unwound and then rewound into a circular coil of radius 2 m. If it is rotated now, with the same speed, under similar conditions, the new peak value of emf developed is

a) 50 V b) 25 V c) 100 V d) 150 V e) 200 V Answer: e) 200 V Solution: e = NΔΦ/Δt peak value =... View Article

A rectangular loop of sides 10 cm and 5 cm with a cut is stationary between the pole pieces of an electromagnet. The magnetic field of the magnet is normal to the loop. The current feeding the electromagnet is reduced so that the field decreased from its initial value of 0.3 T at the rate of 0.02 T/s. If the cut is joined and the loop has a resistance of 2.0 Ω, the power dissipated by the loop as heat is

a) 5 nW b) 4 nW c) 3 nW d) 2 nW Answer: a) 5 nW Solution: Area, A = 10 x 5 = 50 cm2 = 50 x 10-4 m2 dB/dt = 0.02 T/s R =... View Article

There is a uniform magnetic field directed perpendicular and into the plane of the paper. An irregular shaped conducting loop is slowly changing into a circular loop in the plane of the paper. Then

a) current is induced in the loop in the anticlockwise direction b) current is induced in the loop in the clockwise direction c) ac is... View Article

For a set A, consider the following statements:

For a set A, consider the following statements: 1. A⋃P(A) = P(A) 2. {A}⋂ P(A) = A 3. P(A)-{A} = P(A) where P denotes power set. Which of... View Article

Consider the following statements.

Consider the following statements. I.If An is the set of first n prime numbers, Then Un=210 An is equal to {2, 3, 5, 7, 11, 13, 17, 19, 23, 29}... View Article

Which of the following is correct?

Which of the following is correct? 1. n(S ⋃ T) is maximum when n (S ∩ T) is least. 2. If n(U) = 1000, n(S) = 720, n(T) = 450, then least value... View Article

Out of 32 persons, 30 invest in national savings certificates and 17 invest in shares. What is the number of persons who invest in both?

(a) 13 (b) 15 (c) 17 (d) 19 Solution: Let A be the set of people invested in national savings certificates and B be... View Article

In a group of 50 people, two tests were conducted, one for diabetes and one for blood pressure. 30 people were diagnosed with diabetes and 40 people were diagnosed with high blood pressure. What is the minimum number of people who were having diabetes and high blood pressure?

(a) 0 (b) 10 (c) 20 (d) 30 Solution: Let A be the set containing people diagnosed with diabetes and B be the set containing... View Article

There are 600 students in a school. If 400 of them can speak Telugu, 300 can speak Hindi, then the number of students who can speak both Telugu and Hindi is:

(a) 100 (b) 200 (c) 300 (d) 400 Solution: Let A = set of students speaking Telugu B = set of students speaking... View Article

If the cardinality of a set A is 4 and that of a set B is 3, then what is the cardinality of the set AΔ B?

(a) 1 (b) 5 (c) 7 (d) Cannot be determined as the sets A and B are not given Solution: A Δ B is the set of all those elements... View Article