Physics · Science General

Optics and Light Properties

2,019 Questions

Optics and light properties focus on the behavior of light, including reflection, refraction, dispersion, and polarization. This topic also covers the wave nature of light, illumination, and the functioning of optical instruments like microscopes. Questions on these concepts are common in general science sections of SSC, Railways, and State exams.

Reflection and mirrorsRefraction and mediumsLight wave theoriesPolarization and intensity

Optics and Light Properties Questions

Multiple choice evs light, shadows and images what makes things visible nature and sources of light light travels in straight line

Ray optics is valid when characteristic dimension are  

  1. much smaller than wavelength of light.

  2. of same order as wavelength of light

  3. much larger than wavelength of light

  4. none of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ray optics is valid when characteristic dimension are much larger than wavelength of light . The size of obstacle must be much larger than the wavelength of light. If wavelength is comparable to the size of object, then diffraction could happen, but it cannot be explained using ray optics, it will require wave theory of light. 

Multiple choice evs light, shadows and images what makes things visible nature and sources of light light travels in straight line

It is necessary to illuminate the bottom of a well by reflected solar beam when the light is incident at an angle $40^o$ to the vertical. At what angle to the horizontal should a plane mirror be placed?

  1. $65^o$
  2. $70^o$
  3. $75^o$
  4. $80^o$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$\begin{array}{l} i+r=i+i=140 \ or\, \, i={ 70^{ 0 } } \end{array}$

Thus, plane mirror makes an angle of $20^0$ with  vertical and $70^0$  with horizontal.
Therefore  , the correct answer is option $C$.

Multiple choice evs light, shadows and images what makes things visible nature and sources of light light travels in straight line

The illumination on the screen, in case of a movie hall if the distance between the projector and the screen is increased by $1\%$ will be:

  1. increased by $1\%$
  2. decreased by $1\%$
  3. increased by $2\%$
  4. decreased by $2\%$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Projector act as a point source

Hence   $E\propto \dfrac{1}{r^{2}}$
$\dfrac{dE}{E}=2\left(\dfrac{\Delta r}{r}\right)=2\times 1\%=2\%$
As the distance increases, the illumination will decrease.

Multiple choice evs light, shadows and images what makes things visible nature and sources of light light travels in straight line

Pick the only wrong statement in the following :

  1. Light travels with a speed greater than that of sound

  2. Light cannot travel through vacuum

  3. Light travels in a straight line

  4. Light is a wave motion
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Light travels through vacuum for sure as it does not need a material medium for its propagation. Sunlight is the biggest example for this.

Moreover, light has maximum speed in vacuum ,that is, $3\times 10^8$.

Multiple choice physics option c: imaging sunlight - white and coloured sunlight - combination of 7 lights fibre optics basics

The splitting of white light into several colours on passing through a glass prism is due to -

  1. Refraction

  2. Reflection

  3. Interference

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The splitting of white light into its constituent colour is called dispersion. Dispersion occurs because refraction or bending differs with the colour.

Multiple choice physics human eye and colourful world sunlight - white and coloured sunlight - combination of 7 lights fibre optics basics

What does the dispersion of light in a medium imply
i) Lights of different wavelength travel with different speeds in the medium.
ii) Light of any frequency will travel with the same speed in the medium
iii) The refractive index of the medium is different for different wavelength of light

  1. $(i)$ and $(ii)$ only
  2. $(ii)$ and $(iii)$ only
  3. $(i)$ and $(iii)$ only
  4. $(i),(ii)$ and $(iii)$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Dispersion occurs because the refractive index of a medium depends on the wavelength of light. Since refractive index is related to the speed of light in the medium (n = c/v), different wavelengths travel at different speeds, causing them to deviate by different amounts.

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

When the white light is passed through a equilateral prism it splits into seven colours. The phenomena of splitting of white light is called :

  1. $refraction$
  2. $spectrum$
  3. $dispersion$
  4. $scattering$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The splitting of white light into its seven constituent colors when passing through a prism is known as dispersion. Refraction is the bending of light, and the spectrum is the resulting band of colors.