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A : It is necessary to use satellites fo...

A : It is necessary to use satellites for long distance TV transmission.
R : Television signals are not properly reflected by the ionosphere therefore, reflection is effected by satellites.

A

Both 'A' and 'R' are true and 'R' is the correct explanation of 'A'.

B

Both 'A' and ’R' are true and 'R' is not the correct explanation of 'A

C

A' is true and 'R' is false

D

'A' is false and R' is true

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A
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It is necessary ton use satellites for long distance TV transmission. Explain why?

(A): It is necessary to use satellites for long distance T.V transmission (R): The television signals are low frequency signals.

(A) : The sky waves are not used in the transmission of television signals. (R) : Sky waves are mechanical waves.

(A) : For long distance transmission of radio waves, short wave bands are used. (R) : Short waves are reflected from ionosphere.

Long range radio transmission is possible when the radiowaves are reflected from the ionosphere. For this to happen the frequency of the radio waves must be in the range:

Perhaps, the most commonly used mode of communication involves use of free space as a communication channel between transmitter and receiver. The various possible modes of using of free space have been described below Ground wave communication : This mode is used for low frequency as at high frequency, losses become large. This is useful for distance of the order of 1 km. Space wave communication: The signals are transmitted directly from transmitter to receiver. There is no limit to upper frequency, but its range is limited to few hundred kilometers. The range depends on the height of transmitting antenna Sky wave communication : The signals are sent towards sky They are reflected back towards earth by ionosphere. Its range can be above 500 km. But, very high frequencies (above 10 MHz) are not reflected back. Satellite communication: The signals that cannot be reflected back by ionosphere are reflected back by satellite. Moon is a passive satellite of earth. The frequency range allotted to FM radio broadcast is 88 MHz to 108 MHz. Which of the following communication channels can be used for its transmission? A. Sky wave communication only B. Space wave communication only C. Satellite communication only D. Either space wave communication or satellite communication

A : Long distance radio broadcasts use short-wave bands. R : Ionosphere reflects waves in these bands.

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: 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: Short wave band are used for transmission fo radiowaves to a large distance. Statement-2: Short waves are reflected from ionosphere.

AAKASH SERIES-ELECTROMAGNETIC WAVES-EXERCISE -IB
  1. (A ): E.M. waves can show diffraction effect (R) : E.M waves are trans...

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  2. (A ): In electromagnetic wave, electric and magnetic fields oscillate ...

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  3. (A ): The light can travel in vacuum but sound cannot do so (R) : Ligh...

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  4. (A): Gamma rays are more energetic than X-rays (R) : Gamma rays are of...

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  5. Assertion : The earth without its atmosphere would be inhospitably col...

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  6. A : Environmental damage has depleted the ozone layer in the atmosphe...

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  7. (A) : The microwaves are better carriers of signals than radio waves. ...

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  8. Assertion (A) : The presence of CO(2) in the air accelerates corrosio...

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  9. A satellite orbiting close to the surface of earth does not fall down ...

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  10. (A) : The average magnitude of poynting vector vecS is the intensity o...

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  11. A : Long distance radio broadcasts use short-wave bands. R : Ionosp...

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  12. A : It is necessary to use satellites for long distance TV transmissi...

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  13. A : Optical and radio telescopes are built on the ground but X-ray ...

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  14. The ozone layer on the top of the stratosphere is crucial for human su...

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  15. Assertion A pulsar is a source of radio waves that varies in intensity...

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  16. (A) : Quasar emits radiowaves more than radio galaxy. (R) : Quasar has...

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  17. (A) : Dipole oscillations produce electro­magnetic waves. (R) : Accel...

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  18. Assertion (A): wedge(m(H^(o+))) and wedge(m(overset(c)(O)H)) ions are ...

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  19. (A) : In electromagnetic waves electric field and magnetic field lines...

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  20. The transverse nature of electromagnetic waves is proved by which of t...

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