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Worksheet on EM Waves

Q1The electromagnetic waves do not transport -


a) energy

b) charge

c) momentum

d) information



Q2 In an electromagnetic wave the average energy density is associated with -


a) electric field only

b) magnetic field only

c) equally it electric and magnetic fields

d) average energy density is zero



Q3 If there were no atmosphere, the average temperature on earth surface would be -


a) lower

b) higher

c) same

d) 0 degree c



Q4 In which part of earth's atmosphere is the ozone layer present?


a) troposphere

b) stratosphere

c) ionosphere

d) mesosphere



Q5 The ozone layer is earth's atmosphere is crucial for human survival because it -


a) contains ions

b) reflects radio signals

c) reflects ultraviolet rays

d) reflects infra red rays



Q6 Select wrong statement from the following for EMW -


a) are transverse

b) travel with same speed in all medium

c) travel with the speed of light

d) are produced by accelerating charge



Q7 The waves related to tele-communication are -


a) infrared

b) visible light

c) microwaves

d) ultraviolet rays



Q8 The nature of electromagnetic wave is -


a) longitudinal

b) longitudinal stationery

c) transverse

d) transverse stationery



Q9 Greenhouse effect keeps the earth surface -


a) cold at night

b) dusty and cold

c) warm at night

d) moist



Q10 The conduction current is the same as displacement current when source is :-


a) ac only

b) dc only

c) both ac and dc

d) neither dc nor ac



Q11 For a wave propagating in a medium, identify the property that is independent of the others :-


a) Velocity

b) Wavelength

c) Frequency

d) All these depend on each other



Q12 Which wavelength of the Sun is used finally as electric energy ?


a) Radio waves

b) IR waves

c) Visible light

d) Microwaves



Q13 Which of the following statement is false for the properties of electromagnetic waves ?


a) These waves do not require any material medium for propagation

b) Both electric and magnetic field vectors attain the maxima and minima at the same place and same time

c) The energy in electromagnetic wave is divided equally between electric and magnetic vectors

d) Both electric and magnetic field vectors are parallel to each other and perpendicular to the direction of propagation on wave



Q14 The decreasing order of wavelength of infrared, microwave, ultraviolet and gamma rays is :


a) microwave, infrared, ultraviolet, gamma rays

b) gamma rays, ultraviolet, infrared, microwaves

c) microwaves, gamma rays, infrared, ultraviolet

d) infrared, microwave, ultraviolet, gamma gays



Q15 The condition under which a microwave oven heats up a food item containing water molecules most efficiently is :-


a) Infra-red produce heating in a microwave oven

b) The frequency of the microwaves must match the resonant frequency of the water molecules

c) The frequency of the microwaves has no relation with natural frequency of water molecules

d) Microwaves are heat waves, so always produce heating



Q16 If velocity of an electromagnetic wave in a medium is 3 x 10 to the power (8) m/s then find refractive index of medium.


a) 1

b) 2

c) 0.5

d) 0.25



Q17 Out of the following options which one can be used to produce a propagating electromagnetic wave?


a) A charge moving at constant velocity

b) A stationary charge

c) A chargeless particle

d) An accelerating charge



Q18 Assertion :- In electromagnetic waves electric field and magnetic field lines are perpendicular to each other.

Reason :- E and B are self sustaining.


a) A

b) B

c) C

d) D



Q19 Assertion :- Electromagnetic radiations exert pressure.

Reason :- EM-waves carry both momentum & energy.


a) A

b) B

c) C

d) D



Q20 Assertion :- Dipole oscillations produces electromagnetic waves.

Reason :- Accelerated charges produce electromagnetic waves.


a) A

b) B

c) C

d) D



Q21 Assertion :- Sound waves cannot travel in vacuum but light waves can travel in vacuum.

Reason :- Sound waves are longitudinal waves and they cannot be polarised but electromagnetic waves are transverse and they can be polarised.


a) A

b) B

c) C

d) D



Q22 Assertion :- The earth without its atmosphere would be inhospitably cold.

Reason :- All heat would escape it the absence of atmosphere.


a) A

b) B

c) C

d) D



Q23 Assertion :- Environment damage has increased the amount of ozone in the atmosphere.

Reason :- Increases ozone increases amount of UV radiation of earth.


a) A

b) B

c) C

d) D



Q24 Assertion :- The microwaves are better carriers of signals than radio waves.

Reason :- The electromagnetic waves do not require any medium for propagation.


a) A

b) B

c) C

d) D



Q25 Assertion :- Displacement current is a fictitious current and has nothing in common with the conduction current.

Reason :- It was proposed by Maxwell only to satisfy Kirchhoff's junction rule.


a) A

b) B

c) C

d) D



Q26 Assertion :- During discharging there is magnetic field between plates of capacitor.

Reason :- Time varying electric field produces magnetic field.


a) A

b) B

c) C

d) D





ANSWERS

a) b

2) c

3) a

4) b

5) c

6) b

7) c

8) c

9) c

10) c

11) c

12) b

13) d

14) a

15) b

16) a

17) d

18) b

19) a

20) a

21) b

22) a

23) d

24) b

25) d

26) a

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