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 physics light and shadow formation of image by a pinhole camera pinhole camera shadow

A ray of sunlight enters a spherical water droplet $(n = \dfrac{4}{3})$ at an angle of incidence $53^\circ$ measured with respect to the normal to the surface. It is reflected from the back surface of the droplet and re-enters into air. The angle between the incoming and outgoing ray is [Take $\sin \ 53^\circ = 0.8$]

  1. $15^\circ$
  2. $127^\circ$
  3. $138^\circ$
  4. $30^\circ$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The angle between the incoming and outgoing ray is $180^o-53=127$.

Multiple choice physics light and shadow formation of image by a pinhole camera pinhole camera shadow

Light has a wave nature,because-

  1. The light travel in a straight line

  2. Light exhibits phenomenon of reflection and refraction

  3. Lights phenomeno interference

  4. Light exhibits phenomeno of photo electric effect
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Wave nature of light is demonstrated by wave phenomena like interference, diffraction, and polarization. Interference (superposition of waves creating patterns of constructive and destructive interference) cannot be explained by particle theory. Photoelectric effect (option D) demonstrates particle nature, not wave nature. Reflection and refraction can be explained by both theories.

Multiple choice physics light and shadow formation of image by a pinhole camera pinhole camera shadow

Light falls on a plane reflecting surface. For what angle of incidence is the reflected ray normal to the incident ray. 

  1. $60^o$
  2. $45^o$
  3. $90^o$
  4. $30^o$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The incident ray will have an angle of reflection of ${30^0}$ $($made with a surface normal to the mirror surface$).$

Hence,
option $(D)$ is correct answer.

Multiple choice evs magic with mirrors image of an extended object formed by a plane mirror reflection at plane surface introduction to light and mirror

When a ray of light is incident normally on a plane mirror then the angle of reflection will be?

  1. ${0}^{o}$
  2. ${90}^{o}$
  3. ${180}^{o}$
  4. $-{90}^{o}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

As angle of incidence and angle of reflection is always equal hence angle of reflection should be $0°$ as normal to the plane incidence means $0°$ is the angle of incidence from normal.

Multiple choice evs magic with mirrors image of an extended object formed by a plane mirror reflection at plane surface introduction to light and mirror

A monochromatic ray of light in glass strikes the glass air interference normally. which of the following correct?

  1. The ray is totally reflected into glass

  2. The ray passes into air such that the
    refracted ray bends away from the normal

  3. The ray passes into air undeviated and with an increase in its speed.

  4. The ray passes into air with an increase in its frequency.
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice evs magic with mirrors image of an extended object formed by a plane mirror reflection at plane surface introduction to light and mirror

Two plane mirrors A and B are aligned parallel to each other, as shown in figure. A light ray is incident at an angle $30$ at a point just inside one end of A. The plane of incidence coincides with the plane of the figure.The maximum number of times the ray undergoes reflections ( including the first one) before it emerges out is:

  1. $28$
  2. $30$
  3. $32$
  4. $34$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

For two parallel mirrors separated by distance d, the number of reflections is determined by the horizontal distance the ray travels. With an angle of 30 degrees, the ray reflects multiple times until it exits. The standard formula for this geometry results in 30 reflections.

Multiple choice evs magic with mirrors image of an extended object formed by a plane mirror reflection at plane surface introduction to light and mirror

Two plane mirror are inclined to each other such that a ray of light incident on the first mirror $\left( { M } _{ 1 } \right) $ and parallel to the second mirror $\left( { M } _{ 2 } \right) $ is finally reflected form th second mirror $\left( { M } _{ 2 } \right) $ parallel to the first mirror $\left( { M } _{ 1 } \right) $ the angle between the two mirrors will be :

  1. ${ 60 }^{ 0 }$
  2. $75^{ 0 }$
  3. $90^{ 0 }$
  4. $45^{ 0 }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Similar to the previous problem, if the ray reflects off the second mirror parallel to the first, the geometry requires an angle of 60 degrees between the mirrors.

Multiple choice evs magic with mirrors image of an extended object formed by a plane mirror reflection at plane surface introduction to light and mirror

A ray of light is incident on a plane mirror along a vector $\hat {i} + \hat {j} - \hat {k}$, then find the direction of reflected ray if normal is $\hat i + \hat j$

  1. $\hat {i} + \hat {j} - \hat {k}$
  2. $-\hat {i} + \hat {j} - \hat {k}$
  3. $-\hat {i} - \hat {j} - \hat {k}$
  4. $\hat {i} + \hat {j} + \hat {k}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The reflected ray vector r is given by r = i - 2(i.n/n.n)n, where i is the incident ray and n is the normal. Given i = i + j - k and n = i + j, the dot product i.n = 2 and n.n = 2. Thus, r = (i + j - k) - 2(2/2)(i + j) = i + j - k - 2i - 2j = -i - j - k.

Multiple choice evs magic with mirrors image of an extended object formed by a plane mirror reflection at plane surface introduction to light and mirror

The phenomena involves in the reflection of radiowaves by ionosphere is similar to

  1. reflection of light by a plane mirror.

  2. total internal reflection of light in air during a mirage.

  3. dispersion of light by water molecules during the formation of a rainbow.

  4. scattering of light by the particles of air.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The ionosphere is the ionized layer of the Earth's atmosphere and its consists of the ions which are formed due to the UV rays coming from the sun. These free electrons result in the reflection of the radio waves and make them reflected back.


This is same as the mirage formation due to the total internal reflection of the rays when the incident angle is greater than the critical angle.

Multiple choice evs magic with mirrors image of an extended object formed by a plane mirror reflection at plane surface introduction to light and mirror

For which of following condition there is no emergent light whatever may be the angle of incidence?

  1. $ A < 2C $
  2. $ A > C $
  3. $ A > 2C $
  4. $ A < C $
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
For this, we can say that if ${ r } _{ 2 }$ (min) is able to do total internal reflection than definitely all values of ${ r } _{ 2 }$ will perform $TIR$ because min ${ r } _{ 2 }$ has performed that, So, for min ${ r } _{ 2 }$, ${ r } _{ 1 }$ has to be maximum hence $i$ will be maximum,
Applying Snell's law we will get $sin{ r } _{ 1 }=\frac { 1 }{ u } =$ critical angle and for no emergence ${ r } _{ 2 }$ min will be consider us greater than critical angle and hence rest ${ r } _{ 2 }$ will be automatically eligible for $TIR$.
For relation,
${ r } _{ 1 }+{ r } _{ 2 }=A$
We will get ${ r } _{ 1 }+{ r } _{ 2 }=A$
we will get, ${ r } _{ 1 }+{ r } _{ 2 }>2$ (critical angle)
$A>2$ critical angle.
Multiple choice evs nature of things properties of materials grouping and classification of objects sorting materials into groups

Opaque objects:

  1. does not transmit most of the light falling on them

  2. transmit most of the light falling on them

  3. absorb most of the light falling on them

  4. are strong and hard
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

An opaque object is neither transparent (allowing all light to pass through) nor translucent (allowing some light to pass through). When light strikes an interface between two substances, in general, some may be reflected, some absorbed, some scattered, and the rest transmitted. 

Multiple choice evs nature of things properties of materials grouping and classification of objects sorting materials into groups

Transparent substances:

  1. absorb all the light incident on them.

  2. allow light to pass through them.

  3. do not allow light to pass through them.

  4. allow light to pass through them only partially.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Transparent substances allows the light to pass through them. Due to this it is possible to see through the transparent substances. 

Example: We are able to see through the some glasses because they are transparent.

Multiple choice particles of a gas ideal gases physics

The phenomenon of browninan movement may be taken as an evidence of :

  1. kinetic theory of matter

  2. electromagnetic theory of radiation

  3. corpuscular theory of light

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

Since brownian motion explains the collision between particles and their scattering, it is an evidence in support of kinetic theory of gases which is based on movement of particles in force fields of other particles and collision and scattering with them.

Multiple choice electromagnetic spectrum electromagnetic waves physics

Radiation pressure on any surface :

  1. is dependent on wavelength of the light used

  2. is dependent on nature of surface and intensity of light used

  3. is dependent on frequency and nature of surface

  4. depends on the nature of source from which light is coming and on nature of surface on which it is falling.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Radiation pressure is given by   $P _R = \dfrac{(1+\alpha) I}{c}$
where $\alpha$ is the coefficient of reflection of the surface.
For completely reflecting surface  $\alpha =1$
For completely absorbing surface  $\alpha = 0$
So,  radiation pressure depends on the nature of surface on which the light is falling but independent of wavelength of light falling.