Multiple Reflections

Q.

A ray of light strikes a plane mirror XY at an angle of incidence of ${65}^{\circ }$, is reflected from this plane mirror and then strikes a second plane mirror YZ placed at right angles to the first mirror. What is the angle of reflection for the mirror YZ?

Q.

Question 9
Describe the construction of a kaleidoscope.

Q.

State the various uses of a periscope.

Q.

Let $a,b\in R.$ If the mirror image of the point $P(a,6,9)$ with respect to the line $\frac{(x-3)}{7}=\frac{(y-2)}{5}=\frac{(z-1)}{(-9)}$ is $(20,b,-a-9)$ , then $|a+b|$ is equal to:

1. $86$

2. $88$

3. $84$

4. $90$

Q. Question 15
Two mirrors meet at right angles. A ray of light is incident on one at an angle of ${30}^{\circ }$ as shown in Fig. 16.19. Draw the reflected ray from the second mirror.

Q.

How are the two plane mirrors in a periscope arranged:

(a) with respect to one another?

(b) with respect to sides of the tube?

Q.

Explain why, when an object is placed between two plane mirrors inclined at an angle, then multiple images are formed.

Q.

Explain how, a hair dresser makes you see hair at the back of your head after the hair cut is complete.

Q.

How many plane mirror strips are there in a kaleidoscope? How are they arranged?

Q.

What is a periscope? How many mirrors are there in a periscope?

Q. Optical instruments like the periscope and kaleidoscope use the property of ________ in order to create the final image or images.

1. refractions
2. multiple reflections
3. diffractions
4. absorption

Q.

Name the apparatus which is used to obtain a thin beam of light.

Q.

Name an instrument or toy which works by producing multiple reflections from three plane mirrors to from beautiful patterns.

Q.

Name a device which works on the reflection of reflected light.

Q. We can't we see regions behind opaque objects in a well lit room. Which of the following phenomena explains this?

1. Rectilinear propagation of light
2. Reflection of light
3. Virtual image creation by plane mirrors
4. Shadow formation by opaque objects

Q.

Question 6

Two mirrors A and B are placed at right angles to each other as shown in the figure.




A ray of light incident on mirror A at an angle of ${25}^{\circ }$ falls on mirror B after reflection. The angle of reflection for the ray reflected from mirror B would be
(a) ${25}^{\circ }$
(b) ${50}^{\circ }$
(c) ${65}^{\circ }$
(d) ${100}^{\circ }$

Q.

State one use of kaleidoscope.

Q.

The phenomenon of multiple reflections is the working principle of which object?

1. Magnifying lens

2. Periscope

3. Microscope

4. Spectacles

Q. Question 14
How many images of a candle will be formed if it is placed between two parallel plane mirrors separated by 40 cm?

Q. Two plane mirror are inclined to one another at an angle of ${60}^o$. A ray is incident on mirror $M_1$ at an angle $i$. The reflected ray from mirror $M_2$ is parallel to mirror $M_1$as shown in figure. The angle of incidence $i$ is:

Q.

A device which works on the reflection of light from two plane mirrors arranged parallel to one another is:

(a) electroscope

(b) kaleidoscope

(c) periscope

(d) stethoscope

Q.

A student makes a device P by using three long and narrow strips of plane mirrors inclined at ${60}^{\circ }$ to one another which enables him to see beautiful pattern made by pieces of coloured glass bangles. On the other hand, another student makes a device Q by using two plane mirrors arranged parallel to each other which helps him to see a football match clearly even when some very tall persons are sitting in front of him in the ground. What are P and Q?

Q. Analyze the ray diagram of two mirrors inclined at an angle to each other. Find the angle between two mirrors?

1. ${30}^{\circ }$
2. ${90}^{\circ }$
3. ${60}^{\circ }$
4. ${75}^{\circ }$

Q.

When a light ray is incident on one of the two mirrors that are placed at right angle to each other, what can be said about the final reflected ray? It is given that the plane of incident ray and the the two normals is same.

1. It is parallel to the incident ray and is in the same direction as that of the incident ray.

2. It is perpendicular to the incident ray and is in the same direction as that of the incident ray.

3. It is parallel to the incident ray and is in the opposite direction as that of the incident ray.

4. It is perpendicular to the incident ray and is in the opposite direction as that of the incident ray.

Q.

What is time dilation ?

Q. Gaurav is confused, how he can see the back of his head at the hairdresser's shop. Explain the reason to him.​​

Q. Describe the construction of a kaleidoscope. [5 marks]

Q. In the given figure, angle $\theta$ is

1. ${40}^{\circ }$
2. ${60}^{\circ }$
3. ${120}^{\circ }$
4. ${80}^{\circ }$

Q. What is Kaleidoscope?

1. A cylinder with mirrors containing loose colored objects such as beads, pebbles, and bits of glass
2. A cylinder with mirrors
3. None of the above
4. A cylinder containing loose colored objects such as beads, pebbles, and bits of glass

Q. Make a model of kaleidoscope.