Tag: physics

Questions Related to physics

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

Show answer
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

Show answer
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 ($620-750 nm$). 

Name the seven prominent colours of the white light spectrum in order of their increasing frequencies

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. Violet, Indigo, Blue, Green, Yellow, Orange, Red

  2. Red, Orange, Yellow, Green, Blue, Indigo, Violet

  3. Red, Orange, Violet, Yellow, Green, Blue, Indigo

  4. Orange, Yellow, Green, Red, Blue, Indigo, Violet

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Correct Option: B
Explanation:

The range of frequencies from red to violet is 430-790 THz.

Write the approximate wavelengths for red light.

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. $1000A^o$

  2. $2000A^o$

  3. $4000A^o$

  4. $8000A^o$

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Correct Option: D
Explanation:

The range of wavelength for red is $6200-7500$ $A^o$

Write the approximate wavelengths for blue light?

physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

  1. $800A^o$

  2. $1600A^o$

  3. $3200A^o$

  4. $4800A^o$

Show answer
Correct Option: D
Explanation:

The range of wavelengths for blue is $4500-4950$ $A^o$.