Tag: the electromagnetic spectrum

Questions Related to the electromagnetic spectrum

Which of the following is/are not electromagnetic waves?

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. $\beta$ -rays

  2. X-rays

  3. Cosmic rays

  4. Both (a) and (c)

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Correct Option: D
Explanation:

$\beta$ -rays are streams of electron and cosmic rays are waves coming from space. So they are not electromagnetic waves.

UV Rays are useful for 

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. Sterilizing purposes

  2. Detecting purity of gems, ghee, etc

  3. Producing Vitamin D in food of plants and animals

  4. All of the above

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Correct Option: D
Explanation:

All of the options are uses of UV Radiations. 

It can sterilize many substances. Most important application is water sterilization which is used in modern water purifiers.
Fluorescence tests in Ruby and Sapphire allows detecting purity of gems.
Some components of UV light plays key role in Vit D synthesis.

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.