Absorption of Light

Q. Two plane mirrors are arranged at right angles to each other. A ray of light is incident on the horizontal mirror at an angle $\theta$. For what value of $\theta$, the ray emerges parallel to the incoming ray after reflection from the vertical mirror?

1. ${60}^{\circ }$
2. ${30}^{\circ }$
3. ${45}^{\circ }$
4. All of the above

Q. Two plane mirrors $M_1$ and $M_2$ each have length $1\text{m}$ and are separated by $1\text{cm}$. A ray of light is incident on one end of mirror $M_1$ at an angle of ${45}^{\circ }$. How many reflections will the ray have before going out from the other end?

1. $50$
2. $51$
3. $100$
4. $101$

Q. There are two plane mirrors placed at some angle $\theta$ with each other. A ray incident on first mirror (travelling parallel to second mirror) , travels parallel to the first mirror after two successive reflections. Find the angle $\theta$ between the mirrors.

1. ${90}^o$
2. ${60}^o$
3. ${120}^o$
4. ${30}^o$

Q. Three plane mirrors are placed as shown in the figure. A light ray striking the first mirror at an angle of incidence ${60}^{\circ }$, after reflections at all the three mirrors, becomes opposite to the initial direction. Find the value of $\theta$.



Take angle of incidence to be equal at all the mirrors.

1. ${60}^{\circ }$
2. ${150}^{\circ }$
3. ${120}^{\circ }$
4. ${45}^{\circ }$

Q. Two plane mirrors are inclined at ${70}^{\circ }$. A ray incident on one mirror at an angle $\theta$ after reflection falls on the second mirror and is reflected from there parallel to the first mirror, then the angle $\theta$ is

1. ${50}^{\circ }$
2. ${45}^{\circ }$
3. ${30}^{\circ }$
4. ${55}^{\circ }$

Q. A light beam is being reflected by using two mirrors, as in a periscope used in submarines. If one of the mirrors rotates by an angle $\theta ,$ the reflected light will deviate from its original path by the angle:-

1. $2\theta$
2. $0^{\circ }$
3. $\theta$
4. $4\theta$

Q. Three identical flat mirrors are placed mutually perpendicular to each other. The number of distinct images that will be formed due to a point object placed at a point formed by the intersection of lines joining their centres will be (Nearest Integer value)

Q. At what angle from horizontal must we keep the mirror in order to get a vertical reflected ray ?

1. ${15}^{\circ }$
2. ${30}^{\circ }$
3. ${45}^{\circ }$
4. ${60}^{\circ }$

Q. Three identical flat mirrors are placed mutually perpendicular to each other. The number of distinct images that will be formed due to a point object placed at a point formed by the intersection of lines joining their centres will be (Nearest Integer value)

Q. For the given situation shown below, find the angle from horizontal the mirror must be rotated in order to get a vertical reflected ray

1. ${15}^{\circ }$
2. ${30}^{\circ }$
3. ${15}^{\circ }$
4. ${60}^{\circ }$

Q.

Two mirrors meet at right angles. A ray of light is incident on one of the mirrors at an angle of $30$ degrees as shown in figure. Find the reflected angle for the reflection on the second mirror and sketch the reflected ray.

Q. When a drop of oil is spread on a water surface, it displays beautiful colors in daylight because of

1. dispersion of light
2. polarization of light
3. reflection of light
4. interference of light

Q. A mirror is inclined at an angle $\theta$ with the horizontal. If a ray of light is incident at an angle $\theta$ with the surface of the mirror, then the reflected ray makes the following angle with the horizontal.

1. $\theta$
2. $2\theta$
3. $\theta /2$
4. Zero

Q. Two plane mirrors are inclined at ${70}^{\circ }$. A ray incident on one mirror at an angle $\theta$ after reflection falls on the second mirror and is reflected from there parallel to the first mirror, then the angle $\theta$ is

1. ${50}^{\circ }$
2. ${45}^{\circ }$
3. ${30}^{\circ }$
4. ${55}^{\circ }$

Q. Two planes mirrors are inclined at an $\angle \theta$, find $\theta$ if the incident ray is parallel to mirror $M_1$?

Q. The colours seen in the reflected white light from a thin oil film are due to

1. interference
2. diffraction
3. dispersion
4. polarisation

Q. When petrol drops from a vehicle fall over rain water on road surface, colours are seen because of:

1. dispersion of light
2. interference of light
3. absorption of light
4. scattering of light

Q.

Finger prints on a piece of paper may be detected by sprinkling fluorescent

powder on the paper and then looking it into [MP PET/PMT 1988]

1. Mercury light

2. Sunlight

3. Infrared light

4. Ultraviolet light

Q. Two plane mirrors subtend an angle $\theta$. Light incident on one mirror after reflection from the other mirror returns parallel to the original direction. The angle $\theta$ must be

1. ${90}^o$
2. ${45}^o$
3. ${30}^o$
4. ${60}^o$

Q. what is law of reflection and refraction and doplers efect?

Q. Two plane mirrors each $16m$ long are facing each other. The distance between the mirrors is $20cm$. A light incident on one end of one of the mirrors at an angle of ${30}^{\circ }$. How many times is the ray reflected before it reaches the other end ?

Q. Two plane mirrors are arranged at right angles to each other. A ray of light is incident on the horizontal mirror at an angle $\theta$. For what value of $\theta$, the ray emerges parallel to the incoming ray after reflection from the vertical mirror?

1. ${60}^{\circ }$
2. ${30}^{\circ }$
3. ${45}^{\circ }$
4. All of the above

Q. Two plane mirrors inclined at ${70}^0$ . A incident on one mirror at an angle $\theta$ after reflection falls on the second mirror and reflected from there parallel to the first mirror then $\theta$ is :

1. ${45}^{\circ }$
2. ${30}^{\circ }$
3. ${55}^{\circ }$
4. ${50}^{\circ }$

Q. When viewed in white light, soap bubble show colors because of

1. Interference
2. Scattering
3. Diffraction
4. Dispersion

Q.

Finger prints on a piece of paper may be detected by sprinkling fluorescent

powder on the paper and then looking it into [MP PET/PMT 1988]

1. Mercury light

2. Sunlight

3. Infrared light

4. Ultraviolet light

Q. The direction of a ray of light incident on a concave mirror is shown by $PQ$ while directions in which the ray would travel after reflection is shown by four rays marked $1,2,3and4$.
Which of the four rays correctly shows the direction of reflected ray ?

1. $4$
2. $3$
3. $2$
4. $1$

Q. The solar spectrum during a complete solar eclipse is

1. Continuous
2. Emission line
3. Dark line
4. Dark band

Q. Distinguish between frenel and Fraunhoffer diffraction .

Q. Assertion :All the materials always have the same colour, whether viewed by reflected light or through transmitted light. Reason: The colour of material does not depend on nature of light.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q. A light ray interacts with the matter around in several ways. Which of the following are the correct observations?

1. a ray of light bends when it enters from one medium to another
2. a ray of light bounces off a surface in such a way that the incident ray, normal and the reflected ray are in the same plane
3. a ray of light after striking some surfaces, gets absorbed by them
4. A ray of light doesn’t follow the property of rectilinear propagation in a medium other than vacuum