Electromagnetic Waves: Class 12 Previous Year Questions

Electromagnetic Waves questions asked in CBSE board exams

Repeated questions first. Open the free app to see each question as it appeared in the paper, with its marking scheme.

1. ( ) t e ag et w a w t a co sta t ve oc ty. 11. An electromagnetic wave is propagating along x-axis. At any instant, the phase difference (in radian) between the electric field ( E ) and the magnetic field (B) associated with the wave is 1 (A) zero (B)  4 (C) …
   Board 20261 markMCQ
2.  7. Electromagnetic waves used in a diagnostic tool in medicine have a wavelength range 1 (A) 1 nm to 10–3 nm (B) 400 nm to 1 nm (C) 1 mm to 700 nm (D) 0.1 m to 1 mm { } 8  8.   -,   ,           …
   Board 20261 markMCQ
3. Name the electromagnetic waves which are used for 3 (i) detection of fractures in bones (ii) physiotherapy (iii) radar systems Also write their wavelength range.
   Board 20263 marksshort answer
4. An electromagnetic wave passes from vacuum into a dielectric medium with relative electrical permittivity (3/2) and relative magnetic permeability (8/3). Then, its 1 (A) wavelength is doubled and frequency remains unchanged. (B) wavelength is doubled and frequ…
   Board 20261 markMCQ
5. (a) The electric field E of an electromagnetic wave propagating in north direction is oscillating in up and down direction. Describe the direction of magnetic field B of the wave. (b) Are the wave length of radio waves and microwaves longer or shorter than tho…
   Board 20253 marksshort answer
6. The given diagram exhibits the relationship between the wavelength of the electromagnetic waves and the energy of photon associated with them. The three points P, Q and R marked on the diagram may correspond respectively to : Energy· Wavelength (A) X-rays, mic…
   Board 20251 markMCQ
7. Assertion (A) : Out of Infrared and radio waves, the radio waves show more diffraction effect. Reason (R) : Radio waves have greater frequency than infrared waves.
   Board 20251 markAssertion-Reason
8. Electromagnetic waves with wavelength 10 nm are called : (A) Infrared waves (B) Ultraviolet rays (C) Gamma rays (D) X-rays
   Board 20241 markMCQ
9. In the four regions, I, II, III and IV, the electric fields are described as : Region I : Ex = E0 sin (kz t) Region II : Ex = E0 Region III : Ex = E0 sin kz Region IV : Ex = E0 cos kz The displacement current will exist in the region : (A) I (B) IV (C) II (D) …
   Board 20241 markMCQ
10. (a) How are infrared waves produced ? Why are these waves referred to as heat waves ? Give any two uses of infrared waves. OR (b)How are X-rays produced ? Give any two uses of these.
    Board 20232 marksshort answer
11. (a) (i) Depict a plane electromagnetic wave propagating along the x-axis. Write the expressions for its oscillating electric and magnetic fields. (ii) Write three characteristics of electromagnetic waves. 3 OR (b) Name the electromagnetic waves which are produ…
    Board 20221 markvery short
12. State the working principle of an LED. Write any two important advantages and two disadvantages of LED.
    Board 20221 markvery short
13. If electric field associated with an electromagnetic wave is given by E= 30 sin (0.2π × 10-4 m-1x −0.6 π × 104 Hz t) then the direction of propagation of the wave is along, A. 𝑖̂ B. -𝑖̂ C. 𝑘̂ D. -𝑘̂
    Sample paper 2026-271 markMCQ
14. The electric and magnetic fields associated with an electromagnetic radiation in a medium are given as follows: E= 30 sin (2π × 1018rads-1 t + π × 1010 m-1 x) Vm-1 B= 10-7 sin (2π × 1018rad-1 t + π × 1010 m-1 x) T I. What is the refractive index of the medium …
    Sample paper 2026-272 marksshort answer
15. Suppose that the electric field part of an electromagnetic wave in vacuum is E= [3.1 N/C] cos [(1.8 rad/m)y + 5.4 × 108 rad/s)t] (a) What is the direction of propagation of electromagnetic wave? (b) What is the wavelength of electromagnetic wave?
    CBSE practice 2023-242 marksshort answer
16. The diagram below shows the electric field (E) and magnetic field (B) components of an electromagnetic wave at a certain time and location. What is the direction of propagation of the em wave? A. perpendicular to E and B and out of the plane of the paper B. pe…
    CBSE practice 2022-231 markMCQ
17. An electromagnetic wave of frequency 5MHz is passing from air to water then the ratio of the frequency will be (a) 1:5 (b) 5:1 (c) 1:3 (d) 1:1
    CBSE practice 2023-241 markMCQ
18. (a) A radio wave and an infrasonic wave have the same wavelength when travelling through air. Are their frequencies the same or different? Give a reason for your answer. (b) An electromagnetic wave traveling east has a magnetic field that oscillates vertically…
    CBSE practice 2023-243 marksshort answer
19. A capacitor consists of two parallel plates, with an area of cross-section of 0.001 m2, separated by a distance of 0.0001 m. If the voltage across the plates varies at the rate of 108 V/s, determine the value of displacement current through the capacitor.
    CBSE practice 2022-232 marksshort answer

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