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
Weakest rounds: None
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%
Random questions: Yes
Certificate: Yes
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Progressive Test — Guest First Round

Electromagnetic Waves – Progressive Test

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1 / 50

1. A claim says, "All electromagnetic radiations are equally ionising because all travel at speed in vacuum." The claim is

a) correct because wavelength has no relation to photon energy

b) incorrect because electromagnetic waves cannot travel in vacuum

c) correct because equal speed means equal photon energy

d) incorrect because ionising ability depends on photon energy

2 / 50

2. In a charging capacitor, the charge on each plate varies as , where is in and is in . At , the displacement current between the plates is

3 / 50

3. A radio transmitting antenna works because charges in it are made to

a) remain permanently at rest

b) oscillate and therefore accelerate

c) disappear into the surrounding air

d) move with constant speed in one direction only

4 / 50

4. 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

a) maximum negative

b) unrelated to

c) maximum positive

d) zero

5 / 50

5. For the same ideal parallel-plate capacitor, a charge-time graph is a straight line through the origin. If its slope is , the rate of change of electric flux is

6 / 50

6. A source produces electromagnetic waves, and the fields travel outward through empty space. The best description of the travelling wave is that it is

a) a self-propagating pattern of electric and magnetic fields

b) a disturbance carried only by material particles

c) a sound wave with very high frequency

d) a region where electric and magnetic fields both permanently vanish

7 / 50

7. Using and , the speed of a sinusoidal electromagnetic wave can be written as

8 / 50

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

a) electric and magnetic fields cannot exist in vacuum

b) electromagnetic waves carry no field energy

c) the wave fields are mutually linked during propagation

d) electromagnetic waves are really pressure waves in space

9 / 50

9. 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

a) ultraviolet radiation has no electric-field component

b) ultraviolet photons have higher energy

c) red light travels slower than ultraviolet in vacuum

d) red light has shorter wavelength than ultraviolet

10 / 50

10. A graph of versus and versus for the same plane wave shows that the magnetic curve has the same wavelength but much smaller numerical amplitude. The best explanation is that

a) the wave is longitudinal because both graphs are sinusoidal

b) and are in phase, and their amplitudes obey

c) the magnetic field has a different frequency from the electric field

d) the fields are out of phase because they are perpendicular

11 / 50

11. A table compares two types of electromagnetic exposure.

Case	Radiation	Dominant concern
P	Strong infrared beam	Heating
Q	Gamma-ray source	Ionisation and penetration
R	Radio broadcast wave	Highest photon energy
S	Visible red light	Always more ionising than X-rays

The acceptable cases are

a) P, Q, R and S

b) P, R and S only

c) Q and R only

d) P and Q only

12 / 50

12. Read the situation below and answer the question.

A hospital stores a radioactive source used for treatment in a heavily shielded container. The radiation from the source is very penetrating and comes from nuclear processes.

The most suitable radiation type and safety reason are

a) gamma rays, because ionising radiation needs shielding

b) infrared rays, because heat radiation needs nuclear shielding

c) radio waves, because long wavelengths are most ionising

d) microwaves, because microwave beams are nuclear in origin

13 / 50

13. If the frequency of an electromagnetic wave in vacuum is doubled, its wavelength becomes

a) four times

b) half

c) double

d) unchanged

14 / 50

14. 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 P

b) Row R

c) Row S

d) Row Q

15 / 50

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

a) unequal, with the magnetic part always zero

b) unequal, with the electric part always zero

c) unrelated because the fields have different phases

d) equal in their average contributions

16 / 50

16. A plane electromagnetic wave has , , and both fields are in phase. The wave propagates along

17 / 50

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

18 / 50

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

a) high-speed electrons stopped in a heavy metal target

b) special devices producing high-frequency oscillations

c) radioactive nuclear transitions only

d) stationary charges kept at rest on an insulated sphere

19 / 50

19. A plane electromagnetic wave travels along the -axis. If its electric field oscillates along the -axis, the magnetic field must oscillate along

a) the direction opposite to propagation only

b) the -axis

c) the -axis

d) the -axis

20 / 50

20. 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

a) not valid because charges jump across every dielectric gap as conduction current

b) valid because only conduction current can produce magnetic effects

c) valid because the electric field between the plates is constant during charging

d) not valid because changing electric flux produces a current-like magnetic effect

21 / 50

21. A learner writes the chain for a charging capacitor. The most accurate interpretation of this chain is

a) changing charge changes the electric field and flux

b) electric flux changes only after magnetic flux changes

c) changing electric flux prevents electric field formation

d) charge changes only after displacement current crosses as real charge flow

22 / 50

22. For a chosen surface in a time-varying electric-field region, and . The current term that appears in is

23 / 50

23. A wave has and . The speed calculated from these data is

24 / 50

24. A capacitor is being charged, and a surface through the plate gap has but . Another surface with the same boundary cuts the wire. Under ideal conditions, the wire surface should have

a) and

b) and only

c) and

d) and

25 / 50

25. Assertion: The mutual connection between changing electric and magnetic fields helps explain electromagnetic waves.
Reason: A changing electric field can produce a magnetic field, and a changing magnetic field can produce an electric field.

a) Assertion is false, but Reason is true

b) Both Assertion and Reason are true, and Reason explains Assertion

c) Assertion is true, but Reason is false

d) Both Assertion and Reason are true, but Reason does not explain Assertion

26 / 50

26. In a sinusoidal electromagnetic wave, angular frequency and ordinary frequency are related by

27 / 50

27. The basic relation connecting speed , frequency , and wavelength of an electromagnetic wave in vacuum is

28 / 50

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

a) charges flowing from source to receiver through vacuum

b) particles of air moving along the wave path

c) the travelling electric and magnetic fields

d) a static electric field with no magnetic component

29 / 50

29. Assertion: Displacement current is not actual flow of charges across the vacuum gap of a capacitor.
Reason: It is defined through , where is electric flux.

a) Assertion is false, but Reason is true

b) Both Assertion and Reason are true, and Reason explains Assertion

c) Both Assertion and Reason are true, but Reason does not explain Assertion

d) Assertion is true, but Reason is false

30 / 50

30. A law summary is written as: "A changing magnetic flux is associated with an induced electric field." The law being described is

a) Faraday's law

b) Gauss's law for magnetism

c) Gauss's law for electricity

d) the wavelength-frequency relation

31 / 50

31. 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 P

d) Row S

32 / 50

32. A graph-like description says: Region has the largest wavelength, Region has an intermediate wavelength, and Region has the smallest wavelength. If the three regions are radio waves, visible light, and X-rays, the correct assignment is

a) : visible light, : radio waves, : X-rays

b) : radio waves, : X-rays, : visible light

c) : radio waves, : visible light, : X-rays

d) : X-rays, : visible light, : radio waves

33 / 50

33. If the electric field direction of a plane electromagnetic wave is reversed while is kept unchanged, the propagation direction

a) remains unchanged

b) becomes parallel to

c) becomes zero because and still exist

d) reverses

34 / 50

34. Assertion: Electromagnetic waves can travel through vacuum.
Reason: Their propagation is associated with time-varying electric and magnetic fields, not with vibrations of material particles.

a) Assertion is true, but Reason is false

b) Both Assertion and Reason are true, and Reason explains Assertion

c) Assertion is false, but Reason is true

d) Both Assertion and Reason are true, but Reason does not explain Assertion

35 / 50

35. The vector product that gives the direction of propagation of a plane electromagnetic wave is

36 / 50

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

37 / 50

37. Assertion: X-rays require careful use in medical imaging.
Reason: X-rays are ionising electromagnetic radiation and can interact strongly with matter.

a) Both Assertion and Reason are true, but Reason does not explain Assertion

b) Assertion is false, but Reason is true

c) Assertion is true, but Reason is false

d) Both Assertion and Reason are true, and Reason explains Assertion

38 / 50

38. A region of the atmosphere is transparent to visible light but absorbs much of a neighbouring higher-frequency solar radiation. The absorbed neighbouring radiation is most likely

a) radio

b) ultraviolet

c) microwave

d) long-wavelength infrared from remote controls only

39 / 50

39. A summary table for electromagnetic radiation is prepared.

Feature	Low-frequency end	High-frequency end
P. Wavelength	Longer	Shorter
Q. Photon energy	Lower	Higher
R. Common examples	Radio waves	Gamma rays
S. Vacuum speed	Less than	Greater than

The incorrect row is

a) P

b) Q

c) S

d) R

40 / 50

40. A summary line says, " is connected with ." This line refers to

a) Gauss's law for magnetism

b) Faraday's law

c) Gauss's law for electricity

d) Ampere-Maxwell law

41 / 50

41. Use the situation below.

A parallel-plate capacitor is being charged by a battery through connecting wires. A small circular path is chosen around one wire. One surface bounded by the path cuts the wire, while another surface with the same boundary passes between the capacitor plates.

For the same boundary path, the reason both surfaces can give the same magnetic circulation after Maxwell's correction is that

a) the magnetic field is required to vanish at the plate edges

b) the dielectric gap carries free electrons exactly like a copper wire

c) the conduction current in the wire is replaced by zero current everywhere

d) the surface through the gap includes the effect of changing electric flux

42 / 50

42. In the chain "oscillating charge accelerated charge electromagnetic wave," the missing physical link is that

a) wavelength must become infinite before radiation

b) accelerated charge produces radiation

c) electric flux must remain constant

d) magnetic flux must always be zero

43 / 50

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

a) , , propagation along

b) , , propagation along

c) , , propagation along

d) , , propagation along

44 / 50

44. A plane electromagnetic wave is travelling along . Its electric field is along . The magnetic field must be along

45 / 50

45. 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) , because no charge crosses the gap

b) as magnetic current

c) , because the current is divided between plates

d) as displacement current

46 / 50

46. A sinusoidal electromagnetic wave has and . Its speed is

47 / 50

47. A light sail in space is pushed very slightly by sunlight. The best explanation is that sunlight

a) carries momentum and can exert radiation pressure

b) carries no momentum but exerts radiation pressure

c) carries momentum only inside a material medium

d) produces pressure only if converted into sound

48 / 50

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

49 / 50

49. Study the order table and select the row that is correctly arranged from longer wavelength to shorter wavelength.

Row	Order
P	radio waves microwaves infrared visible light
Q	visible light infrared microwaves radio waves
R	X-rays ultraviolet visible light infrared
S	gamma rays radio waves visible light ultraviolet

a) Row P

b) Row R

c) Row S

d) Row Q

50 / 50

50. A radio wave has frequency . Its wavelength in vacuum is closest to

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Electromagnetic Waves Mock Test – Class 12 Physics

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