Tag: the electromagnetic spectrum

Questions Related to the electromagnetic spectrum

We consider the radiation emitted by the human body. Which of the following statements is true :

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. The radiation emitted is in the infrared region

  2. The radiation is emitted only during the day

  3. The radiation is emitted during the summers and absorbed during the winters

  4. The radiation emitted lies in the ultraviolet region and hence is not visible

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Correct Option: A
Explanation:

Every body at all time, at all temperatures emit radiation (except at T = 0), which fall in the infrared region.

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

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. Microwaves, Infrared, ultraviolet, gamma rays.

  2. Infrared, Microwaves, ultraviolet, gamma rays.

  3. ultraviolet, gamma rays, Infrared, Microwaves

  4. Microwaves, gamma rays, Infrared, ultraviolet

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Correct Option: A
Explanation:

The wavelength of the Electromagnetic waves is inversely proportional to the frequency of the wave. The frequency of the gamma rays is highest whereas the ultraviolet, Infrared and microwaves follow in decreasing order.
Therefore, the decreasing order of wavelengths will be opposite to the frequency order. So, the microwaves have the longest wavelength and the gamma rays have the smallest.

Microwave $>$ Infrared $>$ Ultraviolet $>$Gamma ray.

The part of the spectrum of electromagnetic radiation used to cook food is

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. Ultraviolet rays

  2. Cosmic rays

  3. X rays

  4. Microwaves

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Correct Option: D
Explanation:

Microwaves are used to cook food. Microwave oven is a domestic application of these waves.

Which of the following rays is emitted  by a human body?

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. x-rays

  2. visible rays

  3. uvrays

  4. IR rays

  5. none of these

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Correct Option: D
Explanation:

All bodies above absolute zero temperature emit electromagnetic radiation. The wavelength of radiation emitted depends on the temperature of the body. Most of the radiation emitted by the human body is mainly at the wavelength of 12 micron. The wavelength of infrared radiation is between 0.75 to 1000 micron (1 micron = 10-6 metres). Hence , the majority of radiation emitted by human bodies lie in the infrared region.

The frequency from $3\times { 10 }^{ 9 }Hz$ to $3\times { 10 }^{ 10 }Hz$ is

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. high frequency band

  2. super high frequency band

  3. ultra high frequency band

  4. very high frequency band

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Correct Option: B
Explanation:

Frequency from 3 GHz to 30 GHz comes in range of Super High Frequency band.

The spectrum of molecular form the substance is called :

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. band spectrum

  2. line spectrum

  3. absorption spectrum

  4. continuous spectrum

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Correct Option: A
Explanation:

In spectrum. Band spectra is the name given to groups of lines so closely spaced that each group appears to be a band, nitrogen spectrum. Band spectra, or molecular spectra, are produced by molecules radiating their rotational or vibrational energies

Hence the option A is the right answer

Which colour of light travels fastest in any medium except air?

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. Red

  2. Violet

  3. Blue

  4. Orange

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Correct Option: A
Explanation:

Red has maximum wavelength and frequency doesn't change while travelling through a medium. 

Hence, red will travel the fastest since $v=f\lambda$

M and N are two electromagnetic waves.
The ratio $\dfrac{wavelength of M}{wavelength of N}=10^5$. What could M and N be?

M N
A Microwaves Visible light
B Microwaves $\gamma$-rays
C $\gamma$-rays Microwaves
D Visible light Microwaves


physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. A

  2. B

  3. C

  4. D

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Correct Option: A
Explanation:

The wavelength of microwave is around 5 mm and wavelenght of visible around 500 nm

Out of the following , whose velocity is equal to that of light?

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. of $\beta$ rays

  2. of sound waves

  3. of ultrasonic waves

  4. none of these

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Correct Option: D
Explanation:

None of the given above are electromagnetic waves, thus none of them have the velocity of light.

What is the range of wavelength of the spectrum of white light in $nm$?

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. $400nm$ to $500nm$

  2. $500nm$ to $600nm$

  3. $600nm$ to $800nm$

  4. All the above

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Correct Option: D
Explanation:

The range of wavelength of visible light is approximately $400-800 nm$ with violet being at the lower end ($380-450 nm$) and red at the higher end ($620-750 nm$).