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If A and B are two disjoint sets, then which one of the following is correct?

(a) A-B = A-(A⋂B) (b) B-A = A⋂B (c) A⋂B = (A⋃B) (d) none of these Solution: Given that A and B are two disjoints. Therefore A⋂B =... View Article

Which of the following is/are true?

Which of the following is/are true? 1. If A is a subset of the universal set U, then its complement A’ is also a subset of U. 2. If U =... View Article

The cardinality of the set P{P[P(Ø)]} is

(a) 0 (b) 1 (c) 2 (d) 4 Solution: The number of elements in a set is called the cardinality of the set. If set A... View Article

In a B School, there are 15 teachers who teach marketing or finance. Of these, 8 teach finance and 4 teach both marketing and finance. How many teach marketing but not finance?

(a) 15 (b) 20 (c) 11 (d) None of these Solution: Let F denote Finance and M represent Maths. n(F⋃M) = 15 n(F⋂M) = 4... View Article

A survey shows that 61%, 46%, and 29% of the people watched “3 idiots”, “Rajneeti” and “Avatar” respectively. 25% of people watched exactly two of the three movies and 3% watched none. What percentage of people watched all three movies?

(a) 39% (b) 11% (c) 14% (d) 7% Solution: Let A represent the people who watched ‘3 idiots’, B represents the people who watched ‘Rajneeti’... View Article

If X and Y are two sets such that (X ⋃ Y) has 60 elements, X has 38 elements and Y has 42 elements, how many elements do (X ⋂ Y) have?

(a) 11 (b) 20 (c) 13 (d) None of these Solution: Given n (X ⋃ Y) = 60 n(X) = 38 n(Y) = 42 n (X ⋃ Y) = n (X) + n (Y) –... View Article

If n (A) = 115, n (B) = 326, n (A – B) = 47, then what is n(A⋃B) equal to?

(a) 373 (b) 165 (c) 370 (d) 394 Solution: We know, for two sets A and B A - B = A - (A ⋂ B) n (A - B) = n (A) - n... View Article

If A, B, and C are three finite sets, then what is [(A⋃B) ⋂ C]’ equal to?

(a) A’⋃B' ⋂ C' (b) A'⋂B'⋂C' (c) A'⋂B'⋃C' (d) A⋂B⋂C Solution: [(A⋃B) ⋂ C]’ = (A⋃B)’ ⋃ C’ = (A'⋂B'... View Article

Consider the following statements: For non empty sets A, B and C

Consider the following statements: For non empty sets A, B and C. 1. A - ( B - C) = ( A - B) ⋃ C 2. A - (B ⋃ C) = ( A - B) - C Which of the... View Article

If m is the universal set and P is a subset of m, then what is P ⋂ ((P-m) ⋃ (m -P)) equal to?

(a) Ø (b) P' (c) m (d) P Solution: Given that m is the universal set and P is a subset of m. P-m = Ø... View Article

If F(n) denotes the set of all divisors of n except 1, what is the least value of y satisfying [F(20) ⋂ F(16)] ⊆ F(y)?

(a) 1 (b) 2 (c) 4 (d) 8 Solution: F(n) denotes the set of all divisors of n except 1. F(20) = {2, 4, 5, 10, 20}... View Article

Which types of losses do not occur in the transformer?

1) Iron losses 2) Copper losses 3) Mechanical losses 4) Flux leakage Answer: 3) Mechanical losses Solution: Iron losses:- In... View Article

In the transmission of a.c. power through transmission lines, when the voltage is shaped up n times, the power loss in transmission,

1) increase n times 2) Decrease n times 3) Increase n2 times 4) Decrease n2 times Answer: 4) Decrease n2 times Solution:... View Article

Two different loops are concentric & lie in the same plane. The current in outer loop is clockwise & increasing with time. The induced current in the inner loop then, is……….

1) clockwise 2) zero 3) counter clockwise 4) direction depends on the ratio of loop radii Answer: 3) counter clockwise Solution:... View Article

The induction coil works on the principle of

1) self induction 2) mutual induction 3) Ampere's rule 4) Flemidg's right hand rule Answer: 2) mutual induction Solution:... View Article

A solenoid 600 mm long has 50 turns on it and is wound on an iron rod of 7.5 mm radius. Find the flux through the solenoid when the current in it, is 3A. The relative permeability of iron is 600.

1) 1.66 Wb 2) 1.66 nWb 3) 1.66 mWb 4) 1.66 μWb 5) 1.66 pWb Answer: 3) 1.66 mWb Solution: r = 7.5 mm l = 600 mm... View Article

The energy stored in an inductor of self inductance L henry carrying a current of 1 A is

1) L2I 2) -LI2 3) (½) LI2 4) (½)L2I Answer: 3) (½) LI2 Solution: Voltage across inductor, V = L (di/dt)... View Article

A solenoid 30 cm long is made by winding 2000 loops of wire on an iron rod whose cross-section is 1.5 cm². If the relative permeability of the iron is 6000. What is the self inductance of the solenoid?

1) 15 H 2) 2.5 H 3) 3.5 H 4) 0.5 H Answer: 1) 15 H Solution: Self - inductance of the solenoid L = μrμ0N2A/I =... View Article

Two coils have a mutual inductance 5 mH. The current changes in the first coil according to equation I = I₀ sin ωt, where, I₀ =10 A and ω =100 π rad /s. The maximum value of emf in the second coil is

1) 2π 2) 5π 3) π 4) 4π Answer: 2) 5π Solution: ε = M(dI/dt) = Md(I0sinωt)/dt =... View Article

The magnitude of the earth’s magnetic field at a place is B₀ and the angle of dip is δ. A horizontal conductor of length l lying magnetic North South moves Eastwards with a velocity v, the emf induced across the conductor is

1) zero 2) B0 lv sin δ 3) B0 lv 4) B0 lv cos δ 5) B0 sin δ Answer: 2) B0 lv sin δ Solution: When... View Article