Electromagnetic Waves Mock Test – Class 12 Physics

1. A changing electric field in one region and a changing magnetic field in a neighbouring region are part of a travelling disturbance. The best reason this disturbance can continue through vacuum is that

2. A quantity list gives , , , and . The pair that represents currents is

3. A plane electromagnetic wave in vacuum has magnetic-field amplitude . Taking , its electric-field amplitude is

4. A charging capacitor has plate charge increasing at a rate . The rate of change of electric flux between the plates is

5. A charging capacitor has plate area and charge increasing according to . For an ideal parallel-plate capacitor in vacuum, the displacement current between the plates is

6. In Gauss's law for electricity mainly relates electric flux through a closed surface to

7. A magnetic field is detected around the region of a charging capacitor even though no conduction current crosses the plate gap. The most suitable inference is that

8. Consider the following statements for an ideal parallel-plate capacitor during charging.
Statement I: The conduction current in the wire is associated with drift of charge carriers.
Statement II: The displacement-current idea is needed because the electric field between the plates changes with time.
Statement III: The capacitor gap behaves like a metallic wire carrying the same conduction current.

9. A vacuum electromagnetic wave has . Taking , the maximum electric energy density is closest to

10. A statement is made about the electromagnetic spectrum. It says that radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays differ mainly in , , sources, and interactions, but share the same electromagnetic nature. This statement is

11. A plane electromagnetic wave has along and propagates along . The electric field direction must be

12. A table compares four electromagnetic regions for source, effect, and use.

The best judgement about the table is that

13. Use the arrangement described below. A circular path surrounds a wire connected to a charging capacitor. Surface P cuts the wire and has , . Surface Q passes through the capacitor gap and has , . The corrected law gives the same magnetic circulation for both surfaces because

14. Consider the following charge situations.
Statement I: A stationary charge produces an electric field.
Statement II: A steady moving charge produces electric and magnetic fields.
Statement III: An accelerated charge can produce electromagnetic waves.

15. Match each current-related idea with its proper description.

16. The relation for an ideal parallel-plate capacitor shows that the change in flux during charging is caused most directly by

17. A charge moving with constant velocity is compared with a charge that is accelerating. The accelerating charge is special because it can

18. Electric flux through a capacitor gap changes from to in . With , the average displacement current is closest to

19. A spectrum-based safety note says: "Moving from radio waves toward gamma rays generally increases photon energy." This note is

20. A sound wave and an electromagnetic wave are compared in the same region of space. The key difference in their medium requirement is that

21. A microwave signal has frequency . Its wavelength in vacuum is

22. A table lists energy-density expressions for fields in vacuum.

The rows that correctly match the field contribution with its expression are

23. In vacuum, radio waves, visible light, X-rays, and gamma rays have the same

24. A summary table for electromagnetic radiation is prepared.

The incorrect row is

25. A receiving antenna detects a radio wave because the wave's electric field can

26. Read the passage below

The radiation leaves the antenna mainly because the charges are

27. In a charging capacitor, the role of Maxwell's correction can be understood as restoring

28. A row in a student's notes says: "Faraday's law: changing electric flux produces magnetic field." The row needs correction because Faraday's law actually says that

29. In a plane wave, and are plotted against time at a fixed point. The curve reaches exactly when the curve reaches . This observation confirms that

30. Study the table and identify the row that correctly states the vacuum-speed idea.

31. The self-sustaining nature of an electromagnetic wave is mainly based on the fact that

32. A hot metal rod first appears dull red as it is heated and also emits invisible radiation before it glows visibly. The invisible radiation mainly belongs to the

33. A claim says, "During capacitor charging, no conduction current crosses the gap; therefore, the magnetic field in the capacitor region must be absent." The best evaluation is that the claim is

34. A claim about displacement current says, "It must produce heat in vacuum just like conduction current in a resistor, because both have unit ." The best response is that the claim is

35. In a plane electromagnetic wave, no longitudinal field component means that

36. A set of four electromagnetic waves has the following wavelengths in vacuum: , , , and . The wavelength is most likely from the

37. A corrected table of the four standard textbook laws should place "enclosed charge" mainly under

38. In a plane electromagnetic wave with and , the direction set is

39. A photosensitive metal surface emits electrons when ultraviolet light falls on it, but not when low-frequency red light of the same weak intensity is used. The most suitable reason is that

40. Consider the following statements about electromagnetic waves.
Statement I: They are transverse in free space.
Statement II: They can carry energy and momentum.
Statement III: They require a material medium to travel in vacuum.

41. A field record for a plane electromagnetic wave says: at , . For the same point and same instant, if the magnetic field is written as with the same phase, the magnetic field is

42. The statement for an ideal charging capacitor means that

43. In a plane electromagnetic wave travelling through free space, the electric field , magnetic field , and direction of propagation are arranged so that

44. A radiation warning sign is placed near an X-ray source. The main physics reason for shielding is that X-rays

45. A plane electromagnetic wave in vacuum is represented by . The corresponding magnetic field amplitude is

46. At a point in a plane electromagnetic wave in vacuum, the instantaneous electric energy density is . At the same point and instant, the magnetic energy density and the total energy density are

47. Consider the following statements about Maxwell's equations.
Statement I: They include laws for electric flux, magnetic flux, changing magnetic field, and changing electric field.
Statement II: They require the advanced differential form to understand their basic physical meanings at Class level.
Statement III: Maxwell's correction adds the displacement-current idea to Ampere's law.

48. The average intensity of a plane electromagnetic wave in vacuum is also proportional to . If the magnetic-field amplitude becomes , the average intensity becomes

49. For electric field , two commonly used units are

50. A set of four statements is written about the Maxwell framework.
Statement I: Charges are related to electric flux.
Statement II: Isolated magnetic poles are represented by non-zero net magnetic flux through a closed surface.
Statement III: A changing magnetic field can produce an electric field.
Statement IV: A changing electric field can produce a magnetic field.