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# NEET Previous Year Questions (2014-20): Electromagnetic Waves Class 12 Notes | EduRev

## Class 12 : NEET Previous Year Questions (2014-20): Electromagnetic Waves Class 12 Notes | EduRev

The document NEET Previous Year Questions (2014-20): Electromagnetic Waves Class 12 Notes | EduRev is a part of the Class 12 Course Physics Class 12.
All you need of Class 12 at this link: Class 12

Q.1. The ratio of contributions made by the electric field and magnetic field components to the intensity of an electromagnetic wave is : (c = speed of electromagnetic waves)     (2020)
A: 1 : c
B: 1 : c2
C: c : 1
D: 1 : 1

Ans: D
Energy distribution is same so ration of electric field and magnetic field will be 1 : 1

Q.2. Which colour of the light has the longest wavelength?    (2019)
A: Red
B: Blue
C: Green
D: Violet
Ans: A
Solution:

Red has the longest wavelength among the given options.

Q.3. An em wave is propagating in a medium with a velocityThe instantaneous oscillating electric field of this em wave is along +y axis. Then the direction of oscillating magnetic field of the em wave will be along :-    (2018)
A: –z direction
B: +z direction
C: –y direction
D: –x direction
Ans:
B
Solution:

(Therefore, electric field vector is along + y axis)

i.e., direction of magnetic filed vector is along + z direction.

Q.4. In an electromagnetic wave in free space the root mean square value of the electric field is Erms = 6V/m. The peak value of the magnetic field is :-    (2017)
A: 2.83 × 10–8 T
B: 0.70 × 10–8 T
C: 4.23 × 10–8 T
D: 1.41 × 10–8 T
Ans: A
Solution:

Q.5. Out of the following options which one can be used to produce a propagating electromagnetic wave ?    (2016)
A: An accelerating charge
B: A charge moving at constant velocity
C: A stationary charge
D: A charge less particle
Ans:
A
Solution:

An electric charge at rest has electric field in the region around it, but magnetic field is absent. A moving charge produces both electric and magnetic field. When a charge is moving with constant velocity, electric and magnetic field will not change with time. Therefore, no electromagnetic wave will be produced.
But, if the charge is moving with non-zero acceleration, electric and magnetic field will change with space and time. Electromagnetic waves will be produced.
Therefore, accelerated charge emits electromagnetic waves.

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## Physics Class 12

132 videos|259 docs|130 tests

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