Tag: sunlight - combination of 7 lights

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

Dispersion of white light into its constituent colours occurs during

  1. reflection at a plane mirror

  2. reflection at a concave mirror.

  3. internal reflection inside a spherical drop of water

  4. refraction at the boundary of a transparent medium.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Upon entry of white light at the first boundary of a triangular prism, there will be a slight separation of the white light into the component colours of the spectrum. Upon exiting the triangular prism at the second boundary, the separation becomes even greater and ROYGBIV is observed in its splendor. Hence, Dispersion of white light into its constituent colours occurs during refraction at the boundary of a transparent medium.

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

Line spectrum is obtained from the :

  1. Sun

  2. Filament of the bulb

  3. Mercury lamp

  4. Burning coal
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

As a light source, we will use a mercury lamp, which emits light at several discrete wavelengths. The device we are using is called a prism spectrometer because, once the prism is calibrated, it can be used to measure the wavelengths of the lines in the spectra produced by various atoms.

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

A piece of cloth looks red in sun light. If it is held in the blue portion of a solar spectrum, it will appear

  1. Red

  2. Black

  3. Blue

  4. White
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A cloth piece looks red in sun light because it absorbs all the colours of sun light except red, red is reflected to our eyes.

When red cloth piece is held in only the  blue portion of solar spectrum, the blue light will be absorbed by red cloth and as there is no red light is to reflect, therefore no colour will be reflected back i.e. cloth piece will appear black.

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

Which of the following colours of light undergoes the least deviation while passing through a glass prism ?

  1. Red

  2. Blue

  3. Yellow

  4. Green
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Red goes through least deviation because it has highest speed among VIBGYOR.

We know,            $\nu\times \lambda=c$
   Frequency is a constant quantity.
also, 
                           $\mu=\dfrac{velocity\ of\ light\ in\ vacuum}{velocity\ of\ light\ in\ a\ medium}$
.

   so refractive index will be very less for red color and hence show least deviation.


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

The light which refracts most while passing through a prism is

  1. Red

  2. Violet

  3. Indigo

  4. Yellow
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Violet is having shortest wavelength among VIBGYOR. 

We know,            $\nu\times \lambda=c$
   Frequency is a constant quantity.
also, 
                           $\mu=\dfrac{velocity\ of\ light\ in\ vacuum}{velocity\ of\ light\ in\ a\ medium}$
  so, refractive index property for violet will be maximum and it will refract the most.

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

Which of the following colour of light undergoes the maximum deviation while passing a glass prism ?

  1. Red

  2. Blue

  3. Violet

  4. Green
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Violet undergoes maximum deviation while passing through a prism because it has least wavelength , as we know,

            We know,            $\nu\times \lambda=c$
   Frequency is a constant quantity.
also, 
                           $\mu=\dfrac{velocity\ of\ light\ in\ vacuum}{velocity\ of\ light\ in\ a\ medium}$
  so, refractive index property for violet will be maximum and it will refract the most. and will have the greatest deviation.

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

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

  1. $Violet$
  2. $Red$
  3. $Yellow$
  4. $Orange$
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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

  1. Yes

  2. No

  3. Sometimes

  4. When medium is a fibre
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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

  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
Reveal answer Fill a bubble to check yourself
E Correct answer
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 $).

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

What is known as dispersion of light?

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
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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