Tag: spectra

Questions Related to spectra

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

Show answer
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

Show answer
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

Show answer
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

Show answer
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

Show answer
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

Show answer
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.

Show answer
Correct Option: A
Explanation:

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