﻿ Arrange the following electromagnetic radiations per quantum in the order of increasing energy: A: Blue light B: Yellow light C: X-ray D: Radiowave | Communication Systems

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# 1.Arrange the following electromagnetic radiations per quantum in the order of increasing energy: A: Blue light B: Yellow light C: X-ray D: Radiowave D, B, A, C A, B, D, C C, A, B, D C, A, B, D

A.

D, B, A, C

As, we know energy liberated, E = hc/λ

i.e
So, lesser the wavelength greater will be energy liberated by electromagnetic radiations per quantum.

As, order of wavelength is given by

therefore, the order of electromagnetic radiations per quantum.

D<B<A<C

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2.

Choose the correct statement:

• In amplitude modulation, the amplitude of the high-frequency carrier wave is made to vary in proportion to the amplitude of the audio signal.

• In amplitude modulation, the frequency of the high-frequency carrier wave is made to vary in proportion to the amplitude of the audio signal.

• In frequency modulation, the amplitude of the high-frequency carrier wave is made to vary in proportion to the amplitude of the audio signal.

• In frequency modulation, the amplitude of the high-frequency carrier wave is made to vary in proportion to the amplitude of the audio signal.

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3.

A signal of 5 kHz frequency is amplitude modulated on a carrier wave of frequency 2 MHz. The frequencies of the resultant signal is/are:

• 2005 kHz, and 1995 kHz

• 2005 kHz, 2000 kHz and 1995 kHz

• 2000 kHz and 1995 kHz

• 2000 kHz and 1995 kHz

397 Views

4.

A train is moving on a straight track with speed 20 ms-1 .It is blowing its whistle at the frequency of 1000 Hz. The percentage change in the frequency heard by a person standing near the track as the train passes him is (speed of sound = 320 ms-1 ) close to :

• 6%

• 12%

• 18%

• 18%

472 Views

5.

A diode detector is used to detect an amplitude modulated wave of 60% modulation by using a condenser of capacity 250 pico farad in parallel with a load resistance 100 kilo ohm. Find the maximum modulated frequency which could be detected by it.

• 10.62 MHz

• 10.62 kHz

• 5.31 mHz

• 5.31 mHz

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6.

A radar has a power of 1 Kw and is operating at a frequency of 10 GHz. It is located on a mountain top of height 500 m. The maximum distance upto which it can detect object located on the surface of the earth (Radius of earth = 6.4 x 106 m) is

• 80 km

• 16 km

• 40km

• 40km

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7.

This question has Statement 1 and Statement 2. Of the four choices given after the statements, choose the one that best describes the two statements.
Statement 1 - Sky wave signals are used for long distance radio communication. These signals are in general, less stable than ground wave signals.
Statement 2- The state of ionosphere varies from hour to hour, day to day and season to season.

•  Statement 1 is true, statement 2 is false.

• Statement 1 is true, Statement 2 is true, Statement 2 is the correct explanation of Statement 1

•  Statement 1 is true, Statement 2 is true, Statement 2 is not the correct explanation of Statement 1

•  Statement 1 is true, Statement 2 is true, Statement 2 is not the correct explanation of Statement 1

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8.

A sound absorber attenuates the sound level by 20 dB. The intensity decreases by a factor of

• 1000

• 10000

• 10

• 10

491 Views

9.

In a full wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be

• 50 Hz

• 25 Hz

• 100 Hz

• 100 Hz

285 Views

10.

A telephonic communication service is working at carrier frequency of 10 GHz. Only 10% of it is utilized for transmission. How many telephonic channels can be transmitted simultaneously if each channel requires a bandwidth of 5 kHz?

• 2 x 106

• 2 x 105

• 2 x 104

• 2 x 105