Previous Year Papers

Download Solved Question Papers Free for Offline Practice and view Solutions Online.

Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.
Advertisement

 Multiple Choice QuestionsMultiple Choice Questions

1.

Two sources of sound placed close to each other, are emitting progressive waves given by
y1 = 4sin 600π t and y2 = 5 sin 608πt

An observer located near these two sources of sound will hear

  •  4 beats per second  with intensity ratio 25: 16 between waxing and waning

  • 8 beats per second with intensity ratio 25:16 between  waxing and waning

  • 8 beats per second with intensity ratio 81:1 between waxing and waning

  • 8 beats per second with intensity ratio 81:1 between waxing and waning

1229 Views

2.

A source emits electromagnetic waves of wavelength 3m. One beam reaches the observer directly and other after reflection from a water surface, travelling 1.5 m extra distance and with an intensity reduced to 1/4 as compared to intensity due to the direct beam alone. The resultant intensity will be.

  • (1/4) fold

  • (3/4) fold

  • (5/4) fold

  • (9/4) fold


3.

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

  • 1000

  • 10000

  • 10

  • 100


Advertisement

4.

What maximum frequency can be reflected from ionosphere?

  • 5 MHz

  • 6 GHz

  • 5 KHz

  • 500 MHz


A.

5 MHz

The ionosphere extends from a height of 80 km to 300 km. The refractive index of ionosphere is less than its free space value. That is, it behaves as a rarer medium. As we go deep into the ionosphere, the refractive index keeps on decreasing. The bending of beam (away from the normal) will continue till it reaches critical angle after which it will be reflected back. The different points on earth receive signals reflected from different depths of the ionosphere. There is a critical frequency f, (S to 100 MHz) beyond which the waves cross the ionosphere and do not return back to earth.


Advertisement
Advertisement
5.

A hemisphere is positively charged uniformly. The electric field at a point on a diameter away from the centre is directed

  • perpendicular to the diameter

  • parallel to the diameter

  • at an angle tilted towards the diameter

  • at an angle tilted away from the diameter


6.

Assertion:  Sky wave signals are used for long distance radio communication. These signals are in general, less stable than ground wave signals. 

Reason:  The state of ionosphere varies from hour to hour, day to day and season to season.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


7.

Assertion:  Short wave communication over long distance is not possible via ground waves. 

Reason:  The ground waves can bend round the corners ofthe objects on earth.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


8.

For satellite communication which wave is used

  • Space wave

  • Sky wave

  • Ground wave

  • Microwave


Advertisement
9.

If modulation index is 1/2 and power of carrier wave is 2 W. Then what will be the total power in modulated wave?

  • 0.5 W

  • 1 W

  • 0.25 W

  • 2.25 W


10.

Long distance communication between two point or earth is achieved by

  • Space wave communication

  • Sky wave communication

  • Satellite wave communication

  • Line of sight transmission


Advertisement