Electromagnetic Waves Mock Test

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Quiz: Electromagnetic Waves – Progressive Test
Total questions: 400
Questions in this round: 50
Time allotted: 70 minutes
Pass score: 60%
Total rounds: 8
Current round: 1^st
Rounds passed: 0 / 8
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Rounds attempted: 0

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Quiz: Electromagnetic Waves – Certificate Challenge
Total questions: 400
Questions to attempt: 100 random
Time allotted: 100 minutes
Certificate pass score: 70%
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Certificate: Yes
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Progressive Test — Guest First Round

Electromagnetic Waves – Progressive Test

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1 / 50

1. Gauss's law for magnetism is commonly summarized by saying that

a) electric charge is created when magnetic flux is constant

b) light speed equals magnetic flux divided by electric flux

c) net magnetic flux through a closed surface is zero

d) magnetic field can exist only if electric flux is zero

2 / 50

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

a) are low-frequency mechanical sound waves

b) are high-frequency ionising radiation

c) have no interaction with matter

d) must be kept in air to travel

3 / 50

3. A surface-choice record for the same circular loop is shown below.

Surface	Region crossed	Conduction current enclosed
P	Wire connected to capacitor
Q	Gap between capacitor plates

If only the original Ampere law is used, the record would imply

a) two different magnetic circulations for the same boundary loop

b) the same magnetic circulation for both surfaces automatically

c) equal conduction current through wire and dielectric gap

d) zero electric field in the capacitor gap during charging

4 / 50

4. Radio waves are widely used for broadcasting and communication mainly because they

a) are produced only during radioactive nuclear changes

b) are electromagnetic waves handled by antennas

c) are pressure waves detected only by microphones

d) are mechanical waves generated by sound sources

5 / 50

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

a) Faraday's law

b) Gauss's law for magnetism

c) Gauss's law for electricity

d) Ampere-Maxwell circulation law

6 / 50

6. Read the short case and answer the question.

A parallel-plate capacitor is charging in an ideal circuit. A surface cutting the wire encloses a conduction current of . Another surface with the same boundary lies between the plates.

What current-like contribution should the second surface include to keep the magnetic-field calculation consistent?

a) as displacement current

b) , because no charge crosses the gap

c) as magnetic current

d) , because the current is divided between plates

7 / 50

7. In the quantity , the subscript indicates that it is related to

a) frequency

b) electric flux

c) magnetic flux

d) conduction current

8 / 50

8. Consider the following statements about a charging capacitor.
Statement I: Conduction current flows in the connecting wires.
Statement II: The dielectric gap between the plates has ordinary charge flow just like a metallic wire.
Statement III: The electric field between the plates changes as charge accumulates on the plates.

a) I and II only

b) II and III only

c) I and III only

d) I, II and III

9 / 50

9. An electromagnetic wave is best described as a wave made of

a) compressions and rarefactions of air particles

b) only a vibrating magnetic field

c) time-varying electric and magnetic fields

d) only a vibrating electric field

10 / 50

10. A claim says, "Atmospheric windows prove that only selected electromagnetic waves are real waves." The claim is

a) incorrect because no electromagnetic wave can pass through air

b) correct because absorption destroys wave nature

c) correct because only visible light has wavelength

d) incorrect because windows describe transmission, not identity

11 / 50

11. Study the safety classification table and choose the most suitable row.

Row	Radiation	Typical safety description
P	Gamma rays	High-energy ionising radiation requiring shielding and dose control
Q	Radio waves	Always more ionising than X-rays
R	Infrared	Unable to heat matter under any condition
S	Microwaves	Ionising mainly because they have the shortest wavelength in the spectrum

a) Row R

b) Row Q

c) Row S

d) Row P

12 / 50

12. Among the following, the pair most strongly associated with ionising electromagnetic radiation is

a) radio waves and microwaves

b) microwaves and visible red light

c) infrared and radio waves

d) X-rays and gamma rays

13 / 50

13. A circular loop is chosen around a wire connected to a charging parallel-plate capacitor. A surface through the capacitor gap has no conduction current, but the electric flux through it changes at . Taking , the conduction current in the wire that gives the same Ampere-Maxwell current term under ideal conditions is

14 / 50

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

a) emits infrared radiation due to its temperature

b) reflects radio waves from the eyes only

c) produces X-rays continuously by ordinary body heat

d) emits only gamma rays at room temperature

15 / 50

15. 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

a) infrared region

b) gamma-ray region

c) radio-wave region only

d) X-ray region

16 / 50

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

a) and are parallel, but propagation is perpendicular to both

b) , , and propagation direction are mutually perpendicular

c) is along propagation, while is absent

d) all three are parallel to one another

17 / 50

17. If two electromagnetic waves travel in vacuum and wave P has a shorter wavelength than wave Q, then wave P has

a) no definite frequency because wavelength is shorter

b) higher frequency than wave Q

c) the same frequency as wave Q

d) lower frequency than wave Q

18 / 50

18. A claim says, "An electromagnetic wave cannot exert any effect on matter because it has no material particles." The claim is

a) invalid because vacuum always blocks electromagnetic waves

b) valid because radiation pressure exists only for sound waves

c) valid because electromagnetic fields cannot transfer energy

d) invalid because fields can carry energy and interact with matter

19 / 50

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

a) steady currents in conductors

b) changing electric flux in a capacitor gap only

c) waves that require air as a medium

d) regions where no magnetic field can exist

20 / 50

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

a) , , propagation along

b) , , propagation along

c) , , propagation along

d) , , propagation along

21 / 50

21. In a table of Maxwell-equation meanings, the entry "net magnetic flux through a closed surface" should be paired with

a) zero

b) enclosed electric charge

c) frequency

d) displacement current only

22 / 50

22. A graph of electric flux versus time for a charging capacitor is a straight line with positive slope. The graph indicates that

a) the magnetic effect between the plates must be impossible

b) the electric flux is constant and the capacitor is fully unchanging

c) the plate charge must be zero at every instant

d) the electric flux is changing uniformly with time

23 / 50

23. In a plane electromagnetic wave in vacuum, the electric and magnetic fields are said to be in the same phase. This means they

a) differ in phase by

b) reach maxima and zeros together

c) always remain perpendicular in time phase

d) reach maxima at different positions

24 / 50

24. An electromagnetic wave has . Its ordinary frequency is

25 / 50

25. Match each Maxwell equation idea with its qualitative meaning.

Column I	Column II
P. Gauss's law for electricity	1. Changing magnetic field produces electric field
Q. Gauss's law for magnetism	2. Electric flux through a closed surface depends on enclosed charge
R. Faraday's law	3. Net magnetic flux through a closed surface is zero
S. Ampere-Maxwell law	4. Magnetic field is produced by conduction current and changing electric flux

a) P-3, Q-2, R-1, S-4

b) P-2, Q-3, R-1, S-4

c) P-4, Q-3, R-2, S-1

d) P-2, Q-1, R-3, S-4

26 / 50

26. 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

a) correct

b) wrong because radio waves do not contain electric and magnetic fields

c) wrong because only visible light is electromagnetic

d) wrong because gamma rays travel faster than radio waves in vacuum

27 / 50

27. A microwave oven heats food, but microwaves are not usually described as ionising radiation. The best explanation is that microwaves

a) ionise atoms easily because their photon energy is high

b) heat mainly by energy transfer to polar molecules

c) do not transfer any energy to the food

d) are low-intensity gamma rays rather than microwaves

28 / 50

28. A student concludes that electromagnetic waves are "one family" because the same basic wave relation and field nature apply throughout the spectrum. This conclusion is

a) unreasonable because radio waves and gamma rays have the same wavelength

b) reasonable because all regions share electromagnetic field nature

c) reasonable only for waves that need a material medium

d) unreasonable because visible light is the only electromagnetic wave

29 / 50

29. 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.

a) II and III only

b) I and II only

c) I and III only

d) I, II and III

30 / 50

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

31 / 50

31. Study the table and select the row that can represent a plane electromagnetic wave in free space.

Row	Direction of propagation	Direction of	Direction of
P
Q
R
S

a) Row S

b) Row P

c) Row Q

d) Row R

32 / 50

32. A plane electromagnetic wave in vacuum has . Taking , the maximum magnetic energy density is

33 / 50

33. Electromagnetic waves transport energy from one region to another mainly through

a) their electric and magnetic fields

b) the permanent flow of air particles along the wave path

c) isolated magnetic poles carried by the wave

d) a stream of conduction current through empty space

34 / 50

34. In Maxwell's correction, a changing electric field can act as a source of

a) gravitational field only

b) magnetic field

c) sound pressure only

d) electric charge creation

35 / 50

35. In a charging capacitor, charge appears to accumulate on the plates even though no charge crosses the dielectric gap. The process is best understood as

a) electrons crossing the gap exactly as they cross a metal wire

b) charge moving in the wires while the field between plates changes

c) electric field remaining zero until the capacitor is fully charged

d) conduction current ending permanently at the first plate

36 / 50

36. Study the table and select the row that is physically consistent.

Row	Situation	Correct interpretation
P	changes with time in a capacitor gap	Displacement current can exist
Q	in a free-space plane wave	Standard transverse wave geometry
R	Gamma rays have longest wavelength	Lowest photon energy
S	Radio waves and X-rays have same frequency in vacuum	Same spectrum region

a) Row S

b) Row Q

c) Row P

d) Row R

37 / 50

37. A source emits radiation with frequency . Taking , the photon energy is closest to

38 / 50

38. In a circuit containing a charging parallel-plate capacitor, conduction current is present in the connecting wires, but not through the dielectric gap between the plates. The main difficulty for the original Ampere's law is that

a) the electric field between the plates remains zero

b) the capacitor plate charge cannot change with time

c) different surfaces for the same loop enclose different currents

d) the magnetic field around the wire becomes zero during charging

39 / 50

39. X-rays are commonly produced when

a) charges move slowly and uniformly in a straight wire

b) high-speed electrons are stopped by a metal target

c) warm objects emit ordinary heat radiation

d) water molecules rotate in a microwave oven

40 / 50

40. For electric field , two commonly used units are

a) and

b) and

c) and

d) and

41 / 50

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

Row	Expression	Meaning
P		Speed of electromagnetic waves in vacuum
Q		Speed of electromagnetic waves in vacuum
R		Frequency of visible light
S		Wavelength of radio waves

a) Row Q

b) Row S

c) Row P

d) Row R

42 / 50

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

a) photon energy

b) speed

c) wavelength

d) frequency

43 / 50

43. A device emits infrared radiation for warming a painful muscle, while another device emits gamma rays for sterilising equipment. The main safety distinction is that

a) infrared has higher photon energy than gamma rays

b) infrared mainly heats, while gamma rays are ionising

c) gamma rays are outside the electromagnetic spectrum

d) infrared removes electrons more easily than gamma rays

44 / 50

44. A comparison asks why the same electromagnetic family can include both communication waves and medical ionising radiation. The best answer is that

a) communication waves must be mechanical waves, while medical radiation must be electromagnetic

b) only gamma rays contain electric and magnetic fields

c) all are electromagnetic waves, but their frequency and photon energy vary greatly

d) radio waves and gamma rays have identical wavelength

45 / 50

45. A compact passage says:

Four field laws are used together. One tells how charges relate to electric flux. One states that net magnetic flux through a closed surface is zero. One connects changing magnetic field to electric field. One connects conduction current and changing electric flux to magnetic field.

The last sentence of the passage describes

a) Faraday's law

b) Gauss's law for magnetism

c) Gauss's law for electricity

d) Ampere-Maxwell law

46 / 50

46. In a self-propagating electromagnetic wave, energy is transported mainly by

a) a static electric field with no magnetic component

b) the travelling electric and magnetic fields

c) particles of air moving along the wave path

d) charges flowing from source to receiver through vacuum

47 / 50

47. A laboratory note says: "Radiation P can heat tissue mainly by absorption of energy, while radiation Q can ionise atoms directly." A suitable pair for P and Q is

a) microwave and gamma ray

b) gamma ray and radio wave

c) visible red light and microwave

d) infrared and radio wave

48 / 50

48. A charging capacitor has conduction current in its connecting wire. For the same loop around the wire, a surface through the plate gap has no conduction current. The missing physical ingredient in the gap is best described as

a) magnetic flux that remains constant

b) sound-wave pressure due to vibrating air

c) displacement current due to changing electric flux

d) conduction current due to electrons crossing the dielectric

49 / 50

49. Consider the following statements about electromagnetic-wave propagation.
Statement I: The wave can travel through vacuum.
Statement II: The wave carries energy in its electric and magnetic fields.
Statement III: The wave requires a material medium because it is a mechanical vibration.

a) I and III only

b) I and II only

c) I, II and III

d) II and III only

50 / 50

50. In a plane electromagnetic wave travelling through vacuum, the average electric and magnetic energy densities are

a) unequal, with the electric part always zero

b) unrelated because the fields have different phases

c) equal in their average contributions

d) unequal, with the magnetic part always zero

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Electromagnetic Waves Mock Test – Class 12 Physics

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