Electromagnetic Waves Mock Test – Class 12 Physics

1. X-rays are useful in studying crystal structure because their wavelengths are often

2. A plane region in space has a time-varying electric field. According to the Maxwell-correction idea, the immediate magnetic-field-related effect is that the changing electric field can

3. In the visible region, the approximate order of colours from lower frequency to higher frequency is

4. Match the quantities with their physical roles.

5. Radiation pressure is possible because electromagnetic waves carry

6. A material shows fluorescence under ultraviolet radiation but only heating under infrared radiation of suitable intensity. The most suitable interpretation is that

7. A wave has frequency . Its time period is

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

9. A vacuum electromagnetic wave has electric-field amplitude . With , the magnetic-field amplitude is

10. Microwaves lie in the electromagnetic spectrum between

11. Read the passage below

The radiation leaves the antenna mainly because the charges are

12. X-rays are commonly produced when

13. An electromagnetic wave in vacuum has wavelength , while another has wavelength . The frequency of the second wave is

14. A wave quantity record is shown below.

The row that contains an incorrect relation is

15. The most complete statement about electromagnetic waves in vacuum is that they

16. A graph of electric energy density versus is drawn in vacuum. The slope of the graph is

17. A magnetic field in a plane electromagnetic wave is written as . At a point where , the magnetic field component is

18. A data note for a charging capacitor says: "Charge on plates increases uniformly with time." What happens to the electric field between the plates during this interval, assuming the plate area and medium remain unchanged?

19. X-rays and gamma rays are both high-frequency electromagnetic radiations, but in classification they are often distinguished mainly by

20. A night-vision thermal device can detect a person in darkness mainly because the human body

21. A comparison between mechanical waves and electromagnetic waves is made. The feature that belongs specifically to electromagnetic waves in vacuum is

22. At a fixed time, the expression varies from point to point because of

23. A plane-wave expression has the form . The quantity represents

24. Displacement current is introduced to represent the current-like effect produced by

25. Two electromagnetic waves in vacuum have wavelengths and . If the shorter-wavelength wave has photon energy and average intensity , then the longer-wavelength wave with the same field amplitude has photon energy and average intensity

26. A radio signal from a distant transmitter is received clearly over a large region. One suitable atmospheric reason is that

27. Consider the following statements about electromagnetic radiation and matter.
Statement I: Low-frequency radiation can transfer energy without being ionising.
Statement II: High-frequency radiation such as X-rays and gamma rays can be ionising.
Statement III: Ionising ability is decided only by the speed in vacuum.

28. In the electromagnetic spectrum, two neighbouring regions may not have perfectly sharp boundaries. This is mainly because

29. A charge on a parallel-plate capacitor is doubled while the plate area and medium remain unchanged. The electric field and electric flux change as

30. Microwave radiation used in radar and satellite links is commonly generated by

31. 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.

32. Taking and , the value of is approximately

33. A field pair is given by and . The electric and magnetic fields are

34. Sunlight warms a surface on Earth after travelling through space. This is possible because electromagnetic waves

35. Use the graph description below. The horizontal axis represents electromagnetic wavelength. A labelled band near visible wavelengths has high transmission, a labelled ultraviolet band has low transmission due to ozone absorption, and some infrared bands have reduced transmission due to molecular absorption. The graph mainly shows that

36. Use the comparison below.

Which rows are physically consistent?

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

38. In a direction test for a plane electromagnetic wave, and . The wave propagates along

39. 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

40. A thermal camera forms images in darkness by detecting radiation emitted by warm objects. The electromagnetic region most directly involved is

41. A statement says, "Once produced, an electromagnetic wave needs a material medium to keep regenerating its fields." The statement is wrong because

42. Infrared radiation is commonly associated with

43. Radio waves are commonly produced in communication systems by

44. Ampere's circuital law in its original form is most reliable for

45. X-rays are useful in medical imaging mainly because they

46. The conceptual chain from Maxwell's correction to electromagnetic waves is best expressed as

47. At a point in space, a plane electromagnetic wave has at a certain instant. For the paired field with the same phase, the value of at that same point and instant is

48. A plane electromagnetic wave has the electric field . At fixed , the field varies with

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

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