Physics · Science General

Optics and Light Properties

2,013 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 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.

Multiple choice physics wave optics refraction of water waves reflection and refraction at plane surfaces theories on light

Which of the following statement is incorrect about the Raman effect?

  1. Raman effect can be seen by passing a monochromatic beam of light through benzene

  2. During scattering, the wavelength of the light used may change
  3. The wavelength of the monochromatic light used to show the Raman effect is approximately $4358$ $\overset{o}{A}$

  4. In Raman scattering the wavelength of the scattered light is the same as that of the incident light
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The Raman effect involves inelastic scattering of light, meaning the wavelength of the scattered light is different from the incident light (Stokes and anti-Stokes lines).

Multiple choice physics electric circuits introduction to diodes circuit components junction diode and its voltage current characteristics

For detecting the light_______________.

  1. The photodiode has to be forward biased

  2. The photodiode has to be reversed biased

  3. The LED has to connected in forward bias mode

  4. The LED has to be connected in reverse bias mode
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Photo diode is used to detect light. 
In reverse biased condition, the width of depletion region increases as the the applied reverse bias voltage increases across the diode. So, by applying a larger voltage, more of the incident photons are converted to electric current thereby increasing the efficiency.
In forward biased condition, the width of depletion region decreases so only a small portion of the incident photons get converted to electric current and hence the efficiency is less.
Hence photo diode in reverse biased condition detects light.
Therefore the correct option is (B).
Multiple choice evs nature of things objects that float or sink substances that sink or float soluble and insoluble substances

What are transparent materials?

  1. The material which does not allow light to pass through it.

  2. The material which allows light to pass through it.

  3. The material through which light can pass partially.

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

Materials which allow light to completely pass through them without getting scattered are called Transparent material.

Example- a glass of water, clear eyeglasses.

Multiple choice evs nature of things objects that float or sink substances that sink or float soluble and insoluble substances

What do you call a substance through which things are partially visible?

  1. Opaque object

  2. Transparent object

  3. Lustrous object

  4. Translucent object
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The material which does not allow light to pass through it is called opaque and material which allows light to pass through it is called transparent. The material through which light can pass partially is called translucent, e.g. butter paper.

Multiple choice evs nature of things objects that float or sink substances that sink or float soluble and insoluble substances

Translucent substances  __________.

  1. allow the light to pass through it completely

  2. allow the light to pass through it partially

  3. does not allow the light to pass through it

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Those materials that allow some light to pass through them are called translucent and include things like frosted glass and wax paper.