NEET Physics Electromagnetic Waves MCQs

Question: One requires 11 eV of energy to dissociate a carbon monoxide molecule into carbon and oxygen atoms. The minimum frequency of the appropriate electromagnetic radiation to achieve the dissociation lies in

a) ultraviolet region

b) visible region

c) infrared region

d) microwave region

Answer: ultraviolet region

Question: Light with an energy flux of 20 W/cm² falls on a non-reflecting surface at normal incidence. If the surface has an area of 30 cm², the total momentum delivered (for complete absorption) during 30 min is

a) 36 × 10^–4 kg-m/s

b) 1.08 × 10⁷ kg-m/s

c) 36 × 10^–5 kg-m/s

d) 10⁸ × 10⁴ kg-m/s

Answer: 36 × 10^–4 kg-m/s

Question:  If E and B represent electric and magnetic field vectors of the electromagnetic wave, the direction of propagation of electromagnetic wave is along

a) B × E

b) E × B

c) B

d) E

Answer: B × E

Question: The ratio of contributions made by the electric field and magnetic field components to the intensity of an EM wave is

a) 1 : 1

b) c : 1

c) c² : 1

d) None of these

Answer: 1 : 1

More Questions..................................

Question: Light with an energy flux of 25 × 10⁴ Wm^{– 2} falls on a perfectly reflecting surface at normal incidence. If the surface area is 15 cm², the average force exerted on the surface is:

a) 2.50 × 10^{– 6} N

b) 3.0 × 10^{– 6} N

c) 1.20 × 10^{– 6} N

d) None of these

Answer: 2.50 × 10^{– 6} N

Question: Assertion : Environmental damage has increased the amount of ozone in the atmosphere.
Reason : Increase of ozone increases the amount of ultraviolet radiation on earth.

a) Assertion is correct, reason is correct; reason is a correct explanation for assertion

b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion

c) Assertion is incorrect, reason is correct

d) Assertion is correct, reason is incorrect

Answer: Assertion is correct, reason is correct; reason is a correct explanation for assertion

Question: During the propagation of electromagnetic waves in a medium:

a) Electric energy density is equal to the magnetic energy density

b) Electric energy density is half of the magnetic energy density.

c) Electric energy density is double of the magnetic energy density

d) Both electric and magnetic energy densities are zero

Answer: Electric energy density is equal to the magnetic energy density

Question: The energy of the em waves is of the oder of 15 keV. To which part of the spectrum does it belong?

a) X-rays

b) Ultraviolet rays

c) Infra-red rays

d) None of these

Answer: X-rays

Question: Out of the following options which one can be used to produce a propagating electromagnetic wave ?

a) An accelerating charge

b) A chargeless particle

c) A stationary charge

d) A charge moving at constant velocity

Answer: An accelerating charge

Question: Assertion : Radio waves can be polarised.
Reason : Sound waves in air are longitudinal in nature.

a) Assertion is correct, reason is incorrect

b) Assertion is incorrect, reason is correct.

c) Assertion is correct, reason is correct; reason is not a correct explanation for assertion

d) Assertion is correct, reason is correct; reason is a correct explanation for assertion.

Answer: Assertion is correct, reason is incorrect