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04 Feb 2022: The Hindu Analysis

UPSC Current Affairs Preparation: The Hindu Analysis Watch expert analysis of ‘The Hindu’ dated 04 Feb 2022. Important news and views to boost... View Article

04 Feb 2022: UPSC Exam Comprehensive News Analysis

CNA 04 Feb 2022:- Download PDF Here TABLE OF CONTENTS A. GS 1 Related B. GS 2 Related C. GS 3 Related ECONOMY 1. The need to boost labour income... View Article

03 Feb 2022: PIB Summary for UPSC

TABLE OF CONTENTS 1. New methods to transform phenol into key essential ingredients 2. Incentives for adoption of renewable energy 3. Punaura... View Article

SDG India Index 2020-21

The NITI Aayog released the third edition of the Sustainable Development Goals (SDG) India Index 2020-21. What does the SDG India Index indicate?... View Article

The attenuation in optical fibre is mainly due to

1) absorption 2) scattering 3) Neither absorption nor scattering 4) Both (1) and (2) Answer: 4) Both (1) and (2) Solution: Due... View Article

Antenna is

1) inductive 2) capacitive 3) resistive above its resonant frequency 4) resistive at resonant frequency Answer: 1) inductive... View Article

Which of the following four alternatives is not correct?

We need modulation 1) to increase the selectivity 2) to reduce the time lag between transmission and reception of the information signal 3)... View Article

In optical communication system operating at 1200 mm, only 2% of the source frequency is available for TV transmission having a bandwidth of 5 MHz. The number of TV channels that can he transmitted is

1) 2 million 2) 10 million 3) 0.1 million 4) 1 million 5) 0.5 million Answer: 4) 1 million Solution: The frequency for optical... View Article

A diode AM detector with the output circuit consisting of R = 1kΩ and C = 1μF would be more suitable for detecting a carrier signal of

1) 0.1 kHz 2) 0.5 kHz 3) 1 kHz 4) 0.75 kHz 5) 10 kHz Answer: 3) 1 kHz Solution: Here, R=1kΩ=103Ω... View Article

A TV tower has a height 150 m. What is the total population covered by the TV tower, if the population density around the TV tower is 10³ km^-2? The radius of the earth is 6.4 × 10⁶m.

1) 60.288 lakh 2) 40.192 lakh 3) 100 lakh 4) 20.228 lakh Answer: 1) 60.288 lakh Solution: h=150m,R=6.4×106m Average... View Article

The range of frequencies allotted for FM radio is

1) 47 to 230 kHz 2) 47 to 230 MHz 3) 470 to 960 MHz 4) 88 to 108 MHz Answer: 4) 88 to 108 MHz Solution: A maximum frequency... View Article

A signal wave of frequency 12 kHz is modulated with a carrier wave of frequency 2.51 MHz. The upper and lower sideband frequencies are respectively

1) 2512 kHz and 2508 kHz 2) 2522 kHz and 2488 kHz 3) 2502 kHz and 2498 kHz 4) 2522 kHz and 2498 kHz 5) 2512 kHz and 2488 kHz... View Article

1000 kHz carrier wave is amplitude modulated by the signal frequency 200 Hz -4000 Hz. The channel width of this case is

1) 8 kHz 2) 4 kHz 3) 7.6 kHz 4) 3.8 kHz 5) 400 kHz Answer: 1) 8 kHz Solution: Bandwidth = 2f = 2 x 4000 Hz = 8 x 103... View Article

Ozone layer blocks the radiations of wavelength

1) less than 3 × 10-7 m 2) equal to 3 × 10-7 m 3) more than 3 × 10-7 m 4) All of the above Answer: 1) less than 3... View Article

How many photons are emitted by a laser source of 5 × 10^-3 W operating at 632.2 nm in 2s?

1) 3.2 × 1016 2) 1.6 × 1016 3) 4 × 1016 4) None of these Answer: 1) 3.2 × 1016 Solution: Power of laser... View Article

What should be the minimum length of antenna for efficient transmission of signals of wavelength λ?

1) λ/2 2) λ/3 3) λ/4 4) λ/5 Answer: 3) λ/4 Solution: If the radiation and reception of the... View Article

If a radio receiver amplifies all the signal frequencies equally well, it is said to have high

1) fidelity 2) distortion 3) sensibility 4) sensitivity 5) selectivity Answer: 1) fidelity Solution The fidelity of a... View Article

In frequency modulated wave

1) frequency varies with time 2) amplitude varies with time 3) both frequency and amplitude vary with time 4) both frequency and amplitude are... View Article

The antenna current of an AM transmitter is 8 A when only the carrier is sent, but it increases to 8.96 A when the carrier is modulated by a single sine wave. Find the percentage modulation.

1) 60.1% 2) 71 % 3) 80.1% 4) 50.1% Answer: 2) 71 % Solution: We know that (It/Ic)2=1+(m2/2) Here, It=8.96A and Ic=8A... View Article

If E_c= 20 sin 10⁵ πt and E_m= 10 sin 400 πt are carrier and modulating signals respectively, the modulation index is

1) 56% 2) 30% 3) 50% 4) 48% 5) 60% Answer: 3) 50% Solution: Modulation index = Em/Ec = 10/20 = 1/2 = 0.5 x 100 = 50%... View Article