Tag: spectra

Questions Related to spectra

When light passes through a medium that consists of scatters such as water vapour, dust particles, which colour of light experiences highest scattering?

physics spectra sunlight - white and coloured sunlight - combination of 7 lights fibre optics basics

  1. $Violet$

  2. $Red$

  3. $Yellow$

  4. $Orange$

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Correct Option: A
Explanation:

Violet have least wavelength among the visible light spectra.

       According to Rayleigh Criterion,  Scattering probability is proportional to $\dfrac{1}{\lambda^4}$.
So, violet light will be scattered the most.

When light enters a dispersive medium, light wave of different wavelength travels with different velocities.

physics spectra sunlight - white and coloured sunlight - combination of 7 lights fibre optics basics

  1. Yes

  2. No

  3. Sometimes

  4. When medium is a fibre

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Correct Option: A
Explanation:

Yes, speed becomes different for different wavelengths in a particular medium. In a given dispersive medium the speed for different colours is different and due to this phenomenon we can see the spectrum of VIBGYOR.

Assertion: Different colours travel with different speed in vacuum.
Reason : Wavelength of light depends on refractive index of medium.

physics spectra sunlight - white and coloured sunlight - combination of 7 lights fibre optics basics

  1. Both assertion and reason are true but the reason is the correct explanation of assertion

  2. Both assertion and reason are true but the reason is not the correct explanation of assertion

  3. Assertion is true but reason is false

  4. Both the assertion and reason are false

  5. Reason is true but assertion is false

Show answer
Correct Option: E
Explanation:

In vacuum all the colours have same velocity but their velocity changes when they enter in a medium. In the medium their velocity changes due to change in their wavelength.
$v=n\lambda $
If $\lambda $ changes, v also changes for a particular colour therefore, different colours have different wavelength ($\lambda $).

What is known as dispersion of light?

physics spectra sunlight - white and coloured sunlight - combination of 7 lights fibre optics basics

  1. The phenomenon due to which a polychromatic light, like sunlight, splits into its component colours, when passed through a transparent medium

  2. The phenomenon due to which a polychromatic light, like sunlight, splits into its component colours, when passed through a opaque medium

  3. The phenomenon due to which a polychromatic light, like sunlight, splits into its component colours, when passed through a translucent medium

  4. The phenomenon due to which a polychromatic light, like sunlight, do not splits into its component colours, when passed through a transparent medium

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Correct Option: A
Explanation:

When white light pass through a glass prism the white light get scatter in so many colours of light according to it's frequency and the lights are (VIBGYOR) ,this phenomena of scattering of light is called
dispersion of light.

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Due to which property of colours they appear differently though the sunlight is passed through only one medium?

physics spectra sunlight - white and coloured sunlight - combination of 7 lights fibre optics basics

  1. Due to different refractive index with respect to medium

  2. Due to different frequencies with respect to medium

  3. Due to different amplitudes with respect to medium

  4. Due to different colour with respect to medium

Show answer
Correct Option: A
Explanation:

Refraction is a phenomenon that happens when a beam of white light passes through the interface between air and a denser medium, such as glass or water. Light travels more slowly in a denser medium, so it changes direction – or refracts – when it passes through the interface. White light is a mixture of all the wavelengths of light, and each wavelength refracts at a slightly different angle. Therefore, when the beam emerges from the denser medium, it has been split into its component wavelengths. The ones you can see form the familiar rainbow

In the spectrum of white light which color is deviated minimum ?

physics spectra sunlight - white and coloured sunlight - combination of 7 lights fibre optics basics

  1. Red

  2. Yellow

  3. Violet

  4. Blue

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Correct Option: A
Explanation:

Red colour having minimum refractive index and hence undergoes minimum deviation.


Answer-(A)

In spectrum obtained with prism which color is deviated maximum ?

physics spectra sunlight - white and coloured sunlight - combination of 7 lights fibre optics basics

  1. Violet

  2. Red

  3. Green

  4. Orange

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Correct Option: A
Explanation:

Violet colour having higher refractive index and hence undergoes maximum deviation.


Answer-(A)

Which of the following scientists did the pioneering work to understand the splitting of white light in different components ?

physics spectra sunlight - white and coloured sunlight - combination of 7 lights fibre optics basics

  1. Thomas Edison

  2. Albert Einstein

  3. Issac Newton

  4. Archimedes

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Correct Option: C
Explanation:

Newton was the first to understand that white light consists of a mix of light rays, each with a different colour.

The spreading of white light into its component colours is known as.

physics spectra sunlight - white and coloured sunlight - combination of 7 lights fibre optics basics

  1. Dispersion

  2. Deviation

  3. Refraction

  4. Diffraction

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Correct Option: A
Explanation:

$\text{Defination of Dispersion :-}$

Dispersion is the phenomenon of spreading of white light into its component colors. 

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.