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 superposition of waves coherence young's double slit experiment interference

Two coherent sources of light can be obtained by

  1. two different lamps

  2. two different lams of same power and same colour

  3. two different lamps of same power

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

Two sources are said to be coherent if they have exactly same frequency and have zero or constant phase difference. Two coherent source cannot be obtained from two different light sources.

Multiple choice physics superposition of waves coherence young's double slit experiment interference

Two light sources are said to be coherent if they are obtained from:

  1. two ordinary bulbs emitting light of different wavelengths

  2. a single point source

  3. a wide source

  4. two independent point sources emitting light of the same wavelength
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Coherent sources are typically derived from a single point source (e.g., using a beam splitter or double slits) to ensure they share the same initial phase and frequency.

Multiple choice physics superposition of waves coherence young's double slit experiment interference

The sources which can give sustained interference are:

  1. two independent laser sources

  2. two independent light bulbs

  3. two light sources of very large width

  4. two sources far away from one other
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Laser sources produce light waves which are coherent. As sustained interference takes place between waves, which are coherent, we can use two independent laser sources for the same.

Multiple choice physics superposition of waves coherence young's double slit experiment interference

Light waves spreading from two sources produce steady interference only if they have:

  1. congruence

  2. coherence

  3. same intensity

  4. same amplitude
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Interference refers to the interaction of waves that are correlated of coherent with each other. Sustained interference takes place between waves which are coherent.

Multiple choice physics superposition of waves coherence young's double slit experiment interference

Interference of light from two sources can be observed if 

  1. The sources are independent.

  2. The sources are of different frequencies and random phases.

  3. The sources are of different frequency.

  4. The sources are coherent.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Interference of light from two sources can be observed if the sources are coherent . It means that the phase difference between two sources must be constant with time . Two independent sources can't produce an interference pattern .

Multiple choice physics superposition of waves coherence young's double slit experiment interference

For the sustained interference of light, the necessary condition is that the two sources should:

  1. Have constant phase difference

  2. Be narrow

  3. Be close to each other

  4. Of same amplitude
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

To obtain a well defined interference patterns, the intensity at points corresponding to destructive interference must be zero, while intensity at the point corresponding to constructive interference must be maximum. To accomplish this the necessary condition is that the two interference sources must be coherent, that is, they must keep a constant phase difference.

Multiple choice physics superposition of waves coherence young's double slit experiment interference

Sources 1 and 2 emit lights of different wavelengths whereas sources 3 and 4 emit lights of different intensities. The coherence

  1. can be obtained by using sources 1 and 2

  2. can be obtained by using sources 3 and 4

  3. cannot be obtained by any of these sources

  4. since contrast suffers when sources 3 and 4 are used so coherence cannot be obtained by using sources 3 and 4
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

the coherence can be  obtained by using sources 3 and 4 as only the intensities are different so their frequencies can be equal
for a coherent sources frequencies must be equal
option $B$ is correct 

Multiple choice physics superposition of waves coherence young's double slit experiment interference

Two sources of light are said to be coherent, when they give light waves of same

  1. amplitude and phase

  2. wavelength and constant phase difference

  3. intensity and wavelength

  4. phase and speed
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In physics, two wave sources are perfectly coherent if they have a constant phase difference and the same frequency (amplitude may be different).

As $c $ be the speed of light which is constant.
Using, $c= \nu \lambda$
Now same $\nu$ gives same $\lambda.$ for the two light sources.
Example: $y _1= A _1 sin wt$  and $y _2=A _2 sin (wt+\phi) $ where $\phi$ is constant.

Multiple choice physics superposition of waves coherence young's double slit experiment interference

To demonstrate the phenomenon of interference, we require two sources which emit radiation of.

  1. Nearly the same frequency

  2. The same frequency

  3. Different wavelengths

  4. The same frequency and having a definite phase relationship
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
As for an Interference, Two Sources must be Coherent, hence the two sources must have the same frequency and a definite phase relationship.
Multiple choice physics superposition of waves coherence young's double slit experiment interference

Coherent sources for studies in interference of light are obtained from.

  1. Two sources derived from a single source of light having a constant phase difference

  2. Two independent sources of light having a varying phase difference

  3. Two independent sources of light having a constant phase difference

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

Coherent sources are created by splitting light from a single source, ensuring that any phase changes in the original source are reflected equally in both secondary sources, maintaining a constant phase difference.

Multiple choice zoology environmental factors environmental factors and their measurements climate factors marine life

A red shirt

  1. Selectively absorbs red wavelenghts of visible light and scatters the rest

  2. Selectively scatters red wavelenghts of visible light and absorbs the rest

  3. Above all

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

An object appears red because it reflects (scatters) red wavelengths of light and absorbs the other wavelengths in the visible spectrum.

Multiple choice botany living world of plants - plant physiology historical events in photosynthesis history of photosynthesis introduction to photosynthesis

What did Engelmann observe from his prism experiments?

  1. Bacteria could not detect the sites of $O _2$ evolution

  2. Bacteria released excess carbon dioxide in red and blue light
  3. Bacteria accumulated due to increase in temperature caused by increase in $O _2$ concentration

  4. Bacteria are accumulated towards red and blue light
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

T.W Engelmann: He described the first action spectrum of photosynthesis. By using a prism he split sunlight into its spectral components (VIBGYOR) and then illuminated green algae Cladophora placed in a suspension of aerobic bacteria. The bacteria were used to detect the sites of O$ _2$ evolution.

Observation:
1. Bacteria accumulated mainly in the region of blue and red light of the split spectrum.
2. It resembles roughly the absorption spectra of chlorophyll a and b.
Hence, the correct answer is 'Bacteria are accumulated towards red and blue light'.