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 wave optics huygens wave theory and wavefront wave propagation (huygens' construction) theories on light wave behaviour

Which of the following statements indicates that light waves are transverse 

  1. Light waves can travel in vacuum

  2. Light waves show interference

  3. Light waves can be polarized

  4. Light waves can be diffracted
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Polarization is a phenomenon that only occurs with transverse waves, as it requires the oscillation to be perpendicular to the direction of propagation.

Multiple choice physics wave optics huygens wave theory and wavefront wave propagation (huygens' construction) theories on light wave behaviour

On a hot summer night,the refractive index of air is smallest near the ground and increases with height from the ground. When a light beam is directed horizontally , the Huygen's principle leads us to conclude that as it travel,the light beam:

  1. bends downwards

  2. bends upwards

  3. becomes narrower

  4. goes horizontally without any deflection
Reveal answer Fill a bubble to check yourself
C Correct answer
Multiple choice physics wave optics huygens wave theory and wavefront wave propagation (huygens' construction) theories on light wave behaviour

Huygen's originally thought that for the propagation of light waves wavefront is required.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The above statement is true.

As Huygens' principle lets you predict where a given wavefront will be in the future, if you have the knowledge of where the given wavefront is in the present.

Multiple choice physics wave optics huygens wave theory and wavefront wave propagation (huygens' construction) theories on light wave behaviour

Mark the CORRECT statements(s)

  1. Direction of wave propagation is along the normal to wavefront.

  2. For a point source of light, the shape of wavefront can be considered to be plane at very large

    distance from the source.

  3. A point source of light is placed at the focus of a thin spherical lens, then the shape of the wavefront for emerged light may be plane.

  4. The shape of the wavefront for the light incident on a thin spherical lens (kept in vacuum) is plane, the shape of the wavefront corresponding to emergent light would be always spherical.
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Explanation

According to convention, direction of wave propagation is along the normal to wavefront.

The wavefront of a point source of light is spherical. A sphere with large radius is like a plane at its surface. Thus for a point source of light, the shape of wavefront can be considered to be plane at very large distance from the source.
Beam of light from a point source emerges parallel to principle axis when kept at focus of a thin spherical lens. Thus the wavefront emergent from the lens is planar.

Multiple choice physics wave optics huygens wave theory and wavefront wave propagation (huygens' construction) theories on light wave behaviour

A: The corpuscular theory fails in explaining the velocities of light in air and water.
B: According to corpuscular theory, the light should travel faster in a 'denser medium than in a rarer medium.

  1. If both A and B are true but the B is the correct explanation of A

  2. If both A and B are true but the B is not the correct explanation of A

  3. If A is true but B is false

  4. If both the A and B are false

  5. If B is true but A is false
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Corpuscular theory fails to explain the velocity of light in air and water because it predicted light to have more velocity in denser medium where as the fact is just the opposite. So option (a) is correct.

Multiple choice development of plants plant growth growth and development plant growth and development biology

Optimum growth occurs in

  1. Blue light

  2. Red light

  3. White light

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

In chloroplasts, the main pigment present is chlorophyll which is green in color. Growth of plant is affected by the different wavelengths of light as pigments in chloroplasts absorb different wavelengths of light for photosynthesis. White light is a mixture of many wavelengths of colors. Chlorophyll will absorb energies from all visible light except green. Hence exposing white light to a green plants will result in the fastest rate of photosynthesis which in turn result in fastest growth. Hence, optimum growth occurs in white light followed by blue or red.

Thus, the correct answer is option C.

Multiple choice physics reflection of light at curved surfaces problems on mirror and magnification formula derivation of formula for curved mirrors mirror formula and magnification

A light ray travelling parallel to the principle axis of a concave mirror strikes the minor at angle of incidence $\theta$. If the radius of curvature of the mirror is $R$, then after reflection, the ray meets the principle axis at distance $d$ from the centre of curvature, then $d$ is 

  1. $\dfrac {R}{2}$
  2. $R\left(1-\dfrac {1}{2\cos \theta}\right)$
  3. $\dfrac {R}{2\cos \theta}$
  4. $\dfrac {R}{2}(1+\cos \theta)$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For a ray parallel to the axis striking at angle of incidence theta, the distance from the pole to the intersection point is f/cos(theta) = (R/2)/cos(theta). The distance from the center of curvature (at R) is R - (R/2)/cos(theta). None of the options match this standard derivation perfectly, but R/2 is the paraxial approximation.

Multiple choice physics reflection of light at curved surfaces problems on mirror and magnification formula derivation of formula for curved mirrors mirror formula and magnification

A glass hemisphere of radius R and of material having refractive index 1.5 is silvered on its flat face as shown in figure . a small object of height h is located at distance 2R from the surface of hemisphere as shown in the figure. the final image will form

  1. At a distance of R from silvered surface, on the right side

  2. on the object itself

  3. at hemisphere surface

  4. refractive index
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice physics ray optics and optical instruments power of the lens thin lens combination of lenses

A glass slab of thickness 3 cm and refractive index 3/2 is placed on ink mark on a picec of paper, For a person looking at the mark at a distance 2 cm above it, the distance of the mark will paper to be 

  1. 3 cm

  2. 4 cm

  3. 4.5 cm

  4. 5 cm
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The apparent shift due to a glass slab is given by t(1 - 1/n). Here, 3(1 - 1/(3/2)) = 3(1 - 2/3) = 3(1/3) = 1 cm. The mark appears 1 cm closer to the surface. Since the person is 2 cm above the slab (total distance 5 cm from the mark), the apparent distance is 5 - 1 = 4 cm.

Multiple choice physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

Which of the following has largest absorption coefficient?

  1. heavy curtain

  2. cork

  3. marble

  4. open window
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The absorption coefficient of a body is the ratio of the heat radiation absorbed by the body to the total heat radiation incident on it. Since an open window can allow all the radiation into it, it is a good absorber. Hence its coefficient is highest.