Light Test

Result

Light Test - 43

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Weekly Quiz Competition

Question 1
1 / -0

Which of the following letter shaped pipe is most effective to build a Periscope ?

A
A

B
C

C
Z

D
N

Solution

Answer-(C) Z
A periscope lets you look around walls, corners or other obstacles. In a periscope, light from an object strikes the top mirror at 45° and bounces off at the same angle. This sends light directly down the tube and onto the lower mirror. This mirror, also at a 45° angle, reflects light directly to your eye.
Question 2
1 / -0

A bulb is placed between two plane mirrors inclined at an angle of $$ 60^{0}$$.The number of images formed is :

A
$$5$$

B
$$6$$

C
$$4$$

D
$$3$$

Solution

As $$ \dfrac{360^{0}}{\theta}=\dfrac{360^{0}}{60^{0}}=6$$ (which is even)

$$\Rightarrow n=\dfrac{360^{0}}{\theta}-1=6-1=5$$
Question 3
1 / -0

We can see books even though it does not emit light because

A
It is always visible

B
It absorbs light

C
It reflects light

D
Neither absorbs nor reflects light

Solution

Book reflects light and the reflected light reaches our eyes. So, we see the book.
Question 4
1 / -0

The instrument that can be used to see things from a concealed position

A
Periscope

B
Kaleidoscope

C
Telescope

D
Microscope

Solution

A periscope is an instrument for observation from a concealed position. It is light based device which is used to see the back or front side objects with the help of reflection.
Question 5
1 / -0

A man stands symmetrically between two large plane mirrors fixed to two adjacent walls of a rectangular room. The number of images formed are

A
$$4$$

B
$$3$$

C
$$2$$

D
$$6$$

Solution

As man stands symmetrically and hence number of images will be $$\left( \cfrac { 360° }{ \theta } -1 \right) $$
The walls will act as two plane mirror inclined to each other at $$90°\left( \theta =90 \right) $$
$$\therefore$$ No. of images is$$=\cfrac { 360° }{ 90° } -1=4-1=3$$
Question 6
1 / -0

Which among these is the angle of incidence?

A
A

B
B

C
C

D
D

Solution

The angle of incidence is the angle between incident ray and the normal. So, the right answer is B.
Question 7
1 / -0

A plane mirror is placed along the x-axis facing negative y-axis. The mirror is fixed. A point object is moving with $$3\hat{i} \, + \, 4\hat{j}$$ in front of the plane mirror. The relative velocity of image with respect to its object is

A
$$-8\hat{j}$$

B
$$8\hat{j}$$

C
$$3\hat{i} \, - \, 4\hat{j}$$

D
$$-6\hat{i}$$

Solution

Velocity of object, $$\bar{v}_{ob} = 3 \hat{i} + 4 \hat{j} $$
Velocity of image $$\bar{v}_{image} = 3 \hat{i} - 4 \hat{j}$$
Relative velocity of image with respect to its object $$\bar{v}_{rel} \, = \, \bar{v}_{image} \, - \, \bar{v}_{ob} \, = \, (3 \hat{i} \, - \, 4 \hat{j}) \, - \, (3 \hat{i} \, + \, 4 \hat{j}) = -8 \hat{j} $$
Question 8
1 / -0

A man stands symmetrically between two large plane mirrors fixed to two adjacent walls of a rectangular room. The number of images formed are:

A
4

B
3

C
2

D
6

Solution

$$\therefore$$Total number of images=3
$$[M_{1},$$ $$M_{2}$$ and $$(M_{3}$$ or $$M_{4})]$$
$$\because M_{3} \& M_{4}$$ coincides. It should be coincided as same.
$${ M }_{ 1 }\longrightarrow $$image obtained from taking $$M$$ as object on $$L_{1}$$.
$${ M }_{ 2 }\longrightarrow $$image obtained from taking $$M$$ as object on $$L_{2}$$.
$${ M }_{ 3 }\longrightarrow $$image obtained from taking $$M_{1}$$ as object on $$L_{2}$$.
$${ M }_{ 4 }\longrightarrow $$image obtained from taking $$M_{2}$$ as object on $$L_{1}$$.
Question 9
1 / -0

Two plane mirrors are inclined at an angle of $${ 50 }^{ 0 }$$. Then what is the number formed for an object placed in between the mirrors -

A
7

B
8

C
6

D
0

Solution

Given

$$\theta ={50}^{o}$$

No. of images formed, $$n=\cfrac{360}{\theta}$$

$$=\cfrac{360}{50}$$

$$=7$$

$$n=7$$
Question 10
1 / -0

How many images of an object are formed if two adjacent walls and the ceiling of a rectangular room are mirror surfaced?

A
3

B
7

C
6

D
9

Solution

User

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Re-Attempt Weekly Quiz Competition

Light Test - 43

Result

Light Test - 43

Score

-

Rank

-

SHARING IS CARING

Question 1

A

C

Z

N

Solution

Question 2

$$5$$

$$6$$

$$4$$

$$3$$

Solution

Question 3

It is always visible

It absorbs light

It reflects light

Neither absorbs nor reflects light

Solution

Question 4

Periscope

Kaleidoscope

Telescope

Microscope

Solution

Question 5

$$4$$

$$3$$

$$2$$

$$6$$

Solution

Question 6

A

B

C

D

Solution

Question 7

$$-8\hat{j}$$

$$8\hat{j}$$

$$3\hat{i} \, - \, 4\hat{j}$$

$$-6\hat{i}$$

Solution

Question 8

4

3

2

6

Solution

Question 9

7

8

6

0

Solution

Question 10

3

7

6

9

Solution

User

Question Analysis

My Perfomance

Score

-

Rank

-

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