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The F-layer persists in earth's atmosphe...

The F-layer persists in earth's atmosphere at night because

A

It is a top most layer in earth's atmosphere which is highly ionized and inspite of recombination, ionization persists to some degree.

B

The actual air density in the F layer is low but ionization density in this layer is high so most of the molecules in this layer are in ionized state at night.

C

Due to low density of air in layer, the molecular have a large free path. The molecular collision rate is low.

D

All the above

Text Solution

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The correct Answer is:
D
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AAKASH SERIES-COMMUNICATION SYSTEMS -Exercise - IA (Sky Wave propagation)
  1. When a sky wave is reflected on to the ground

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  2. The height of F(2) layer is (1) 240 km to 400 km in day time (2) 3...

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  3. The main role of F(2) layer in communication is

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  4. Sky wave have a wavelength

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  5. Transmission via sky waves is impossible for the frequencies

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  6. The layer responsible for reflection of ratio wave is

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  7. Read the following (1) Refractive index can be less than one (2) M...

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  8. With increases of ionic density, the R.I, of ionosphere

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  9. The highest frequency of transmitted wave that is returned to the eart...

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  10. The highest frequency of transmitted wave that is returned to the eart...

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  11. The expression for critical frequency is

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  12. Two waves A & B of frequencies 2 MHz & 3 MHz & 3 MHz respectively are ...

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  13. E.M. waves with frequencies greater than critical frequency of ionosph...

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  14. Skip zone in radio wave transmission is that range where

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  15. The F-layer persists in earth's atmosphere at night because

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  16. If sky wave with a frequency of 60 MHz is incident on D-region at angl...

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  17. If a radio-receiver amplifies all the signal frequencies equally well,...

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  18. Refractive index of ionosphere is

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  19. Three waves A, B and C of frequencies 1600 kHz, 5 MHz and 60 MHz, resp...

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  20. Which of the following frequencies will be suitable for beyond the hor...

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