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If the electron in the hydrogen atom jumps from third orbit to second orbit the wavelength of the emitted radiation in term of Rydberg constant is

1) 6/5R 2) 36/5R 3) 64/7R 4) None of these Answer: 2) 36/5R Solution: Wavelength of emitted radiation is given by... View Article

In the hydrogen atom, an electron jumps from a bigger orbit to a smaller orbit so that radius of smaller orbit is one-fourth of radius of bigger orbit. If speed of electron in bigger orbit was v, then speed in smaller orbit is

1) v/4 2) v/2 3) v 4) 2v Answer: 4) 2v Solution: r ∝ n2rbig/rsmall =n2big/n2small =(4/1) ⇒nbig/nsmall =2... View Article

Which of the following value is the correct order of nuclear density?

1) 5 × 105 kg/m3 2) 9 × 1010 kg/m3 3) 3 × 1021 kg/m3 4) 2 × 1017 kg/m3 Answer: 4) 2 × 1017 kg/m3... View Article

An antenna is a device

1) That converts electromagnetic energy into radio frequency signal 2) That converts radio frequency signal into electromagnetic energy 3)... View Article

An AM wave has 1800 watt of total power content. For 100% modulation the carrier should have power content equal to

1) 1000 watt 2) 1200 watt 3) 1500 watt 4) 1600 watt Answer: 2) 1200 watt Solution: Total power content, Pt = 1800 watt... View Article

A silicon optical fibre has a core refractive index of 1.50 and a cladding refractive index of 1.47 what is the numerical aperture of the fibre?

1) 0.90 2) 0.60 3) 0.45 4) 0.30 Answer: 4) 0.30 Solution: Core refractive index, n1 = 1.50 Cladding refractive index, n2 =... View Article

In satellite communication 6 GHz frequency is used for ___________ and 4 GHz frequency is used for

1) Uplink, downlink 2) Downlink, uplink 3) Modulation, demodulation 4) Demodulation, modulation Answer: 1) Uplink, downlink... View Article

Statement-1 :- Modulated wave is received directly on a headphone

Statement-2 :- High frequency waves are beyond audible range.

(a) Statement-1 is true, statement-2 is true. Statement-2 is a correct explanation for statement-1. (b) Statement-1 is true, statement-2 is... View Article

Statement-1:- Microwaves and not radio waves are used in satellite communication.

Statement-2:-The wavelength of microwaves is much shorter than that of radio waves. Hence microwaves do not disperse or diffract like radio waves.

(a) Statement-1 is true, statement-2 is true. Statement-2 is a correct explanation for statement-1. (b) Statement-1 is true, statement-2 is... View Article

Statement-1 :- sky waves are not used in the transmission of T.V signals

Statement-2 :- T.V signals have a frequency range of 100 to 200 MHz

(a) Statement-1 is true, statement-2 is true.Statement-2 is a correct explanation for statement-1. (b) Statement-1 is true, statement-2 is... View Article

To transmit 1 Khz frequency signal, wave length of the signal should be ___________m

1) 3 x 103 2) 3 x 105 3) 3 x 107 4) 3 x 1010 Answer: 2) 3 x 105 Solution: f = 1 KHz = 103Hz we know, c = f × λ... View Article

Electromagnetic waves with frequencies greater than the critical frequency of ionosphere cannot be used for communication using sky wave propagation, because

1) the refractive index of the ionosphere becomes very high for f > fc 2) the refractive index of the ionosphere becomes very low for f >... View Article

A G.P. consists of an even number of terms. If the sum of all the terms is 5 times the sum of terms occupying odd places, then the common ratio is

(a) 5 (b) 1 (c) 4 (d) 3 Solution: Let the G.P be a, ar, ar2 … S = a + ar + ar2 + ….to 2n terms =... View Article

a, b, c are in G.P. with 1 < a < b < n, and n > 1 is an integer. log_a n, log_b n, log_c n form a sequence. This sequence is which one of the following?

(a) Harmonic progression (b) Arithmetic progression (c) Geometric progression (d) None of these Solution: Given that a, b, c are in... View Article

The value of the infinite product 6^1/2 ×6^1/4× 6^1/8×6^1/16×…is

(a) 6 (b) 36 (c) 216 (d) ∞ Solution: 61/2 ×61/4× 61/8×61/16×… = 6(1/2 + 1/4 + 1/8 + 1/16 +... View Article

Let S_n (1 ≤ n ≤ 9) denotes the sum of n terms of series 1 + 22 + 333 + ……………..+ 9999999999, then for 2 ≤ n ≤ 9

(a) Sn - Sn-1 = (1/9)(10n - n2 + n) (b) Sn = (1/9)(10n - n2 + 2n - 2) (c) 9(Sn - Sn-1) = n(10n -1) (d) none of these Solution: Given... View Article

Given that α, γ are the roots of the equation Ax² – 4x + 1 = 0, and β, δ the roots of the equation Bx² – 6x + 1 = 0, the values of A and B such that α, β, γ, and δ are in H. P. are

(a) A = 3, B = 8 (b) A = - 3, B = 8 (c) A = 3, B = - 8 (d) None of these Solution: α, β, γ, and... View Article

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