CBSE Class 12 Physics Chapter-8 Important Questions – Free PDF Download
Free PDF download of Important Questions with Answers for CBSE Class 12 Physics Chapter 8 – Electromagnetic Waves 1 Mark Questions prepared by expert Physics teachers from latest edition of CBSE(NCERT) books only by CoolGyan to score more marks in CBSE board examination.
CBSE Class 12 Physics Chapter-8 – Electromagnetic Waves
CBSE Class 12 Physics Important Questions Chapter 8 – Electromagnetic Waves
1 Mark Questions
1. The charging current for a capacitor is 0.25A. What is the displacement current across its plates?
Ans. Displacement current remains the same as charging current and is equal to 0.25A.
2. Write the following radiations in a descending order of frequencies: red light, x – rays, microwaves, radio waves
Ans. X – rays, Red light, Microwaves and Radio waves.
3. How does the frequency of a beam of ultraviolet light change, when it goes from air into glass?
Ans. There is no effect on the frequency of ultraviolet light.
4. What is the ratio of speed of gamma rays and radio waves in vacuum?
Ans. One.
5. It is necessary to use satellites for long distance TV transmission. Why?
Ans. Television signals are not reflected back by the layer of atmosphere called ionosphere thus TV signals from air earth station are reflected back to the earth
by means of an artificial satellite
6. What is the role of ozone layer in the atmosphere?
Ans. It absorbs all the harmful ultraviolet radiations thus protecting us from reaching the dangerous effects of uv radiations.
7. What is the nature of waves used in radar?
Ans. Microwaves are used in Radar.
8. What physical quantity is the same for X-rays of wavelength 10-10 m, red light of wavelength 6800 
and radio waves of wavelength 500 m?
Ans. The speed of light (
m/s) in a vacuum is the same for all wavelengths. It is independent of the wavelength in the vacuum.