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 biology movement and locomotion in living organisms movements in plants coordination in plants tropic and nastic movements in plants

Curvature in phototropic movements occur 

  1. At the tip

  2. Behind the tip

  3. Far away from the tip

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

Charles Darwin studied phototropism by covering different parts of oat coleoptiles and subjecting them to light from one direction. When he covered or removed coleoptile tip, phototropic response did not occur and concluded that phototropic bending in the zone of elongation was controlled by the tip. The movements which allow organs of plants to move in or the other directions is called movements of curvature. His demonstration that the site of photoreception at the shoot tip and the location of curvature are separable. From his observations, Darwin was able to propose that a transmissible substance produced in the tip is responsible for inducing curvature in lower regions of the plant. This insightful discovery eventually lead to the discovery of first plant hormone - auxin.

Multiple choice biology movement and locomotion in living organisms movements in plants coordination in plants tropic and nastic movements in plants

A decapitated plant exposed to unilateral light

  1. Bends away from source of illumination

  2. Bends towards the source of light

  3. Shows zigzag curvature

  4. Does not show bending movement
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The plant growth regulator that brings about the growth and bending of stem towards light is present only at the tip, i.e the apex of the stem.
So, when the tip is removed or decapitated, the part containing the PGR auxin is also lost. Hence, a decapitated plant does not show any bending when exposed to unilateral light.
Thus, the correct answer is D 'Does not show bending movement'
Multiple choice chemistry metals physical properties of metals and non-metals some physical properties of metals general characteristics and uses of metals

Explain lustre.

  1. Shining by reflecting light

  2. Deformation into thin sheets

  3. Deformation into rods

  4. Free electrons to conduct electricity and heat
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Lustre is the way light interacts with the surface of a crystal, rock, or mineral. There are various types of lustre like greasy lustre, metallic lustre, dull lustre etc.

Multiple choice physics wave optics difference between interference and diffraction explaining wave phenomena diffraction

When monochromatic light is replaced by white light in Fresnel's biprism arrangement, the central fringe is

  1. colored

  2. white

  3. dark

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

When white light refracts from the biprism, all colours would form coherent sources at different positions according to their refractive indices. However the position of their central fringe would be same, and hence they would all combine at that position to again give a white fringe.

Multiple choice physics wave optics difference between interference and diffraction explaining wave phenomena diffraction

A beam of natural light falls on a system of $6$ polaroids, which are arranged in succession such that each polaroid is turned through ${30}^{o}$ with respect to the preceeding one. The percentage of incident intensity that passes through the system will be

  1. $100$%
  2. $50$%
  3. $30$%
  4. $12$%
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

If $I$ is the final intensity and $I _0$ is the initial intensity then,

$I=\dfrac{I _0}{2}(\cos^2{30})^5$
$\dfrac{I _0}{I}=\dfrac{1}{2}\times \left(\dfrac{\sqrt3}{2}\right)^{10}=0.12=12 percent$

Multiple choice physics wave optics difference between interference and diffraction explaining wave phenomena diffraction

The correct relation between the angle of diffraction $\phi $ and the glancing angle $\theta $ in Davisson-Germer experiment will be:

  1. $\theta = {90^0} - \frac{\phi }{2}$
  2. $\phi = \frac{\phi }{2} - {90^0}$
  3. $\theta = {90^0} - \phi $
  4. $\phi = {90^0} - \phi $
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In the Davisson-Germer experiment, the glancing angle theta is the angle between the incident beam and the crystal planes, and the diffraction angle phi is the angle between the incident and scattered beam. They are related by theta = 90 - phi/2.

Multiple choice physics wave optics difference between interference and diffraction explaining wave phenomena diffraction

A light wave is incident normally on a glass slab of refractive index $1.5$. If $4\%$ of light gets reflected and the amplitude of the electric field of the incident light is $30\ V/m$,then the amplitude of the electric field for the wave propogating in the glass medium will be:

  1. $10\ V/m$
  2. $24\ V/m$
  3. $30\ V/m$
  4. $6\ V/m$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$P _{refracted}=\frac {  96}{ 100 } P _1$
$\Rightarrow K _2A^2 _t=\frac {  96}{ 100 }K _1A^2 _i$
$\Rightarrow r _2A^2 _t=\frac {  96}{ 100 }r _1A^2 _i$
$\Rightarrow A^2 _t=$ $ \frac {  96}{ 100 } \times$ $\frac { 1 }{ 3 } {2} $ $\times (30)^2$
$A _t\sqrt { \frac { 64 }{ 100 }\times(30)^2  } =24$

Multiple choice physics wave optics difference between interference and diffraction explaining wave phenomena diffraction

A diffraction is obtained by using a beam of red light. What will happen if the red light is replaced by the blue light 

  1. Bands will narrower and crowd
    full together

  2. Bands become broader and further apart

  3. No change will take place

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

Fringe width beta = lambda * D / d. Since the wavelength of blue light is shorter than that of red light, the fringe width decreases, causing the bands to become narrower and more crowded.

Multiple choice physics wave optics difference between interference and diffraction explaining wave phenomena diffraction

In the Fresnel bi-prism experiment, the refractive index for the bi-prism is $\mu=3/2$ and fringe width obtained is $0.4mm$. If the whole apparatus is immersed as such in water then the fringe width will become(refractive index of water is $4/3$).

  1. $0.3mm$
  2. $0.225mm$
  3. $0.4mm$
  4. $1.2mm$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In a fresnel bi-prism, fringe width,$\omega _{medium}=\dfrac{D\lambda _{medium}}{d _{medium}}$

where $\lambda _{medium}=\dfrac{\lambda _{vacuum}}{\mu _{medium}}$
and $d _{medium}\propto A(\dfrac{\mu _{bi-prism}}{\mu _{medium}}-1)$
Here $\mu _{medium}=\dfrac{4}{3}$ and $\mu _{bi-prism}=\dfrac{3}{2}$
Hence $\dfrac{\omega _{water}}{\omega _{vacuum}}=3$
Hence, $\omega _{water}=1.2mm$