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A metal disc of radius 100 cm is rotated at a constant angular speed of 60 rads ^-1 in a plane at right angles to an external field of magnetic induction 0.05 Wbm^-2. The end’ induced between the centre and a point on the rim will be

1) 3 V 2) 1.5 V 3) 6V 4) 9 V Answer: 2) 1.5 V Solution: Given, ω=60rad/s B=0.05Wb/m2 R=100cm=1m Induced... View Article

A transformer is often filled with oil. The oil used should have

1) low viscosity 2) high dielectric strength 3) low boiling point 4) high thermal conducting Answer: 2) high dielectric strength Solution: ... View Article

If the coefficient of mutual induction of the primary and secondary coils of an induction coil is 5 H and a current of 10 A is cut-off in 5 × 10^-4 s, the emf inducted (in volt) in the secondary coil is

a) 5 x 104 b) 1 x 105 c) 25 x 105 d) 5 x 106 Answer: b) 1 x 105... View Article

The inductance of a coil is L =10 H and resistance R = 5 Ω. If the applied voltage of the battery is 10 V and it switches off in 1 ms, find induced emf of the inductor.

1) 2 × 104 V 2) 1.2 × 104 V 3) 2 × 10-4 V 4) None of these Answer: 1)... View Article

In a step-up transformer, the relation between the number of turns in primary (N_p) and the number of turns in secondary (N_s ) coils is

1) Ns is greater than Np 2) Np is greater than Ns 3) Ns is equal to Np 4) Np... View Article

In a survey of 400 students in a school, 100 were listed as taking apple juice, 150 as taking orange juice and 75 were listed as taking both apple as well as orange juice. Then, which of the following is/are true?

150 students were taking at least one juice. 225 students were taking neither apple juice nor orange juice. (a) Only... View Article

In a group of 500 students, there are 475 students who can speak Hindi and 200 can speak Bengali. What is the number of students who can speak Hindi only?

(a) 275 (b) 300 (c) 325 (d) 350 Solution: Total number of students = 500 Let H be the set... View Article

A dinner party is to be fixed for a group of 100 persons. In this party, 50 persons do not prefer fish, 60 prefer chicken and 10 do not prefer either chicken or fish. The number of persons who prefer both fish and chicken is.

(a) 20 (b) 22 (c) 25 (d) None of these Solution: Let n(F) denotes the number of persons who prefer... View Article

If A = {4n + 2| n is a natural number} and B = {3n| n is a natural number}, then what is (A⋂B) equal to?

(a) {12n2 + 6n| n is a natural number} (b) {24n – 12| n is a natural number} (c) {60n... View Article

If A and B are subsets of a set X, then what is {A⋂(X-B)}⋃B equal to?

(a) A⋃B (b) A⋂B (c) A (d) B Solution: Given that A and B are subsets of a set X.... View Article

Each student in a class of 40, studies at least one of the subjects English, Mathematics and Economics. 16 study English, 22 Economics and 26 Mathematics, 5 study English and Economics, 14 Mathematics and Economics and 2 study all the three subjects. The number of students who study English and Mathematics but not Economics is

(a) 7 (b) 5 (c) 10 (d) 4 Solution: Total number of students = 40 Let x be number of... View Article

If A and B are two sets, then (A – B) ⋃(B – A) ⋃ (A ⋂ B) is equal to

(a) Only A (b) A ⋃ B (c) (A⋃B)’ (d) None of these Solution: (A – B) ⋃(B – A)... View Article

If A, B, C are three sets, then what is A – (B – C) equal to?

(a) A – (B ⋂ C) (b) (A – B) ⋃ C (c) (A – B) ⋃ (A ⋂ C)... View Article

Let S = the set of all triangles, P = the set of all isosceles triangles, Q = the set of all equilateral triangles, R = the set of all right-angled triangles. What do the sets P ⋂ Q and R – P represents respectively?

(a) The set of isosceles triangles; the set of non- isosceles right-angled triangles (b) The set of isosceles triangles; the... View Article

Which of the following sets is a finite set?

(a) A = {x : x ∈ Z and x2 – 5x + 6 = 0} (b) B = {x... View Article

If P(A) denotes the power set of A and A is the void set, then what is the number of elements in P{P{P{P(A)}}}?

(a) 0 (b) 1 (c) 4 (d) 16 Solution: If set A has n elements then P(A) has 2n elements.... View Article

Let A = {x| x ≤ 9, x ∈ N}. Let B = {a, b, c} be the subset of A where (a + b + c) is a multiple of 3. What is the largest possible number of subsets like B?

(a) 12 (b) 21 (c) 27 (d) 30 Solution: Given A = {x| x ≤ 9, x ∈ N} =... View Article

Which of the following is a singleton set?

(a) {x : |x| = 5, x ∈ N} (b) {x : |x| = 6, x ∈ Z} (c) {x... View Article

Let S be a set of all distinct numbers of the form P/Q , where p, q ∈ {1, 2, 3, 4, 5, 6}. What is the cardinality of the set S?

(a) 21 (b) 23 (c) 32 (d) 36 Solution: Number of elements taken at a time = 2 i.e. (p... View Article

Which of the following is true?

(a) a∈ {{a}, b} (b) {b, c} ∈ {a, {b, c}} (c) {a, b} ∈ {a, {b, c}} (d) None... View Article

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