8. Electromagnetic Waves

*नोट: यह सेक्शन रिवीजन के लिए है। अपना ज्ञान परखने के लिए ऊपर दिए गए क्विज़ में भाग लें।

1. Speed of light (c) in vacuum is?
   A) 3 x 10^8 m/s  |  B) 3 x 10^10 m/s  |  C) 2 x 10^8 m/s  |  D) 3 x 10^5 m/s
2. Nature of Electromagnetic waves is?
   A) Longitudinal  |  B) Transverse  |  C) Both  |  D) Static
3. Concept of Displacement Current was given by?
   A) Faraday  |  B) Ampere  |  C) Maxwell  |  D) Hertz
4. Which has the highest frequency?
   A) Radio waves  |  B) Infrared  |  C) Gamma rays  |  D) Visible light
5. Waves used in Radar system?
   A) Microwaves  |  B) Infrared  |  C) UV  |  D) X-rays
6. Waves used in remote controls?
   A) Radio  |  B) Infrared  |  C) Visible  |  D) UV
7. Who absorbs harmful UV rays from sun?
   A) Oxygen  |  B) Ozone layer  |  C) Nitrogen  |  D) CO2
8. Who discovered X-rays?
   A) Maxwell  |  B) Hertz  |  C) Roentgen  |  D) Newton
9. Wavelength range of visible light is approx:
   A) 400nm - 700nm  |  B) 1nm - 100nm  |  C) 700nm - 1mm  |  D) None
10. Velocity of EM waves in vacuum depends on:
    A) Frequency  |  B) Intensity  |  C) Properties of medium  |  D) Independent (all same)
11. Which waves cannot travel in vacuum?
    A) Light  |  B) Radio  |  C) Sound waves  |  D) X-rays
12. Infrared waves are also called?
    A) Cool waves  |  B) Heat waves  |  C) Visible waves  |  D) None
13. Who experimentally confirmed EM waves?
    A) Maxwell  |  B) Hertz  |  C) Marconi  |  D) J.C. Bose
14. Waves used for TV signals?
    A) Radio waves  |  B) Infrared  |  C) UV  |  D) Visible
15. Waves responsible for Greenhouse effect:
    A) X-rays  |  B) Infrared  |  C) UV  |  D) Gamma
16. Angle between Electric field (E) and Magnetic field (B) in EM wave:
    A) 0°  |  B) 45°  |  C) 90° (Perpendicular)  |  D) 180°
17. Formula for speed of light in vacuum:
    A) 1 / √(µ₀ε₀)  |  B) √(µ₀ε₀)  |  C) µ₀/ε₀  |  D) ε₀/µ₀
18. Use of Ultraviolet (UV) rays:
    A) Water purification  |  B) Bone treatment  |  C) Fog vision  |  D) TV operation
19. Ratio of amplitudes E₀/B₀ of EM wave is equal to:
    A) c (Speed of light)  |  B) 1/c  |  C) µ₀  |  D) ε₀
20. EM waves carry what with them?
    A) Charge  |  B) Energy & Momentum  |  C) Mass  |  D) None
21. Comes just after visible light (shorter λ) in spectrum:
    A) Infrared  |  B) UV  |  C) X-ray  |  D) Radio
22. EM waves are produced by:
    A) Static charge  |  B) Accelerated charge  |  C) Uniform velocity charge  |  D) Neutral particle
23. Phase of E and B vectors is:
    A) In phase  |  B) 90° diff  |  C) 180° diff  |  D) None
24. Ozone layer is located in which part of atmosphere?
    A) Troposphere  |  B) Stratosphere  |  C) Mesosphere  |  D) Ionosphere
25. EM waves travel in vacuum because they are:
    A) Longitudinal  |  B) Non-mechanical  |  C) Mechanical  |  D) Scalar
26. Wavelength of Microwaves is:
    A) Less than radio  |  B) More than radio  |  C) Equal to gamma  |  D) None
27. X-rays used in medicine because they:
    A) Can penetrate opaque objects  |  B) Are soft  |  C) Are colored  |  D) Are scalar
28. Speed of light in denser medium:
    A) Increases  |  B) Decreases  |  C) Remains constant  |  D) Zero
29. Pressure exerted by EM waves is:
    A) Atmospheric  |  B) Radiation Pressure  |  C) Liquid pressure  |  D) Zero
30. Impedance of free space is approx:
    A) 377 Ohm  |  B) 100 Ohm  |  C) Zero  |  D) Infinity
31. Frequency 30 MHz. Wavelength in vacuum?
    A) 1 m  |  B) 10 m  |  C) 100 m  |  D) 3 m
32. If E₀ = 300 V/m, then B₀ is?
    A) 10⁻⁶ T  |  B) 10⁻⁷ T  |  C) 10⁻⁵ T  |  D) 300 T
33. Intensity of light from 100W bulb varies with distance r as:
    A) 1/r  |  B) 1/r²  |  C) r  |  D) r²
34. Source of Gamma rays?
    A) Accelerated electron  |  B) Radioactive decay  |  C) Hot body  |  D) Radio antenna
35. If frequency is doubled, speed in vacuum:
    A) Doubles  |  B) Halves  |  C) Unchanged  |  D) Four times
36. Poynting Vector represents?
    A) Rate of energy flow  |  B) Charge flow  |  C) Magnetic force  |  D) Field direction
37. AM radio band range is approx:
    A) 530 kHz - 1700 kHz  |  B) 88 MHz - 108 MHz  |  C) 1 GHz - 100 GHz  |  D) None
38. Current between capacitor plates during charging?
    A) Conduction  |  B) Displacement current  |  C) Both  |  D) None
39. Total Maxwell equations for EM waves:
    A) 2  |  B) 3  |  C) 4  |  D) 5
40. Lowest frequency (longest λ) in visible light?
    A) Violet  |  B) Blue  |  C) Red  |  D) Green
41. Ratio of electric and magnetic energy density contribution:
    A) 1:1 (Equal)  |  B) 2:1  |  C) 1:2  |  D) None
42. 0.1 nm wavelength wave belongs to:
    A) Radio  |  B) X-ray  |  C) Infrared  |  D) UV
43. Direction of propagation of EM waves is parallel to:
    A) E  |  B) B  |  C) E x B  |  D) None
44. If ε₀ = 8.85x10⁻¹² and µ₀ = 4πx10⁻⁷, speed is:
    A) 3x10^8 m/s  |  B) 1x10^8 m/s  |  C) 9x10^9 m/s  |  D) None
45. Used to detect broken hand bones:
    A) Gamma rays  |  B) UV  |  C) X-rays  |  D) Infrared