Tag: electromagnetic waves

Questions Related to electromagnetic waves

EM waves travels with a speed of

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. 260m/s

  2. $\displaystyle 3\times { 10 }^{ 8 }m/s$

  3. $\displaystyle 22\times { 10 }^{ 18 }m/s$

  4. 2m/s

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Correct Option: B
Explanation:

EM waves travel with the same speed in vacuum (or air) which is same as the speed of light ie. $\displaystyle 3\times { 10 }^{ 8 }m/s$

Which of the following sources of light is different from others

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. Sunlight

  2. White light

  3. Light from a bulb

  4. Sodium light

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Correct Option: D
Explanation:

Sunlight is reffered as white light. It consist of seven colours,i.e VIBGYOR

Most energetic radiations and fluorescence are properties of 

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. Gamma rays

  2. UV Rays

  3. Infrared Rays

  4. Radio waves

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Correct Option: A
Explanation:

Gamma Rays are most energetic Radiations. Since they have high penetrating power, they can cause fluorescence on fluorescent materials like ZnS.

Gamma rays have frequency(f)

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. $f > 3 \times 10^{19} Hz$

  2. $7.5 \times 10^{14}Hz < f < 3 \times 10^{16} Hz$

  3. $<3 \times 10^7 Hz$

  4. None of the above

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Correct Option: A
Explanation:

Frequency of gamma rays is greater than $3 \times 10^{19} Hz$

EM waves are

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. Longitudinal waves

  2. Transverse waves

  3. Both

  4. None

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Correct Option: B
Explanation:

Electromagnetic waves are transverse waves. The electromagnetic waves of entire wave length range do not require any material we drive for their propagation.

Where are radiowaves used?

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. Radar, radio and tv communications

  2. Microwave ovens

  3. Photographic films

  4. sterilizing purpose

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Correct Option: A
Explanation:

Radiowaves are used in-

1. Radar communications
2. Radio and TV communications

Electromagnetic waves exhibit the property of

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. Reflection

  2. Refraction

  3. Total internal reflection

  4. Both A and B

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Correct Option: D
Explanation:

EM waves exhibit the properties of reflection and refraction. In refraction, when an EM wave passes from one medium to the another, its direction to travel,speed and wavelength changes, but frequency remains unchanged.

EM waves are

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. deflected by electric and magnetic waves

  2. not deflected by electric and magnetic waves

  3. sometimes deflected sometimes not deflected

  4. none of the above

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Correct Option: B
Explanation:

EM waves are not deflected by electric and magnetic field. They exhibit the property of reflection and refraction.

What are the harmful effects of ultraviolet radiations?

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. It can cause skin cancer.

  2. It contributes to global warming.

  3. It contributes to greenhouse effect.

  4. It can cause depletion of natural resources.

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Correct Option: A
Explanation:

Long exposure to ultraviolet radiations can cause health hazards like skin cancer.

Which of the following are use of microwaves?

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. They are used for satellite communication.

  2. They are used for analysis of atomic and molecular structure.

  3. They are used cooking in microwave ovens.

  4. All of the above.

Show answer
Correct Option: D
Explanation:

Microwaves are used in the following applications:

1. Satellite communications
2. Radar communications
3. Analysis of atomic and molecular structure
4. Cooking in microwave ovens