Light Test

Result

Light Test - 46

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Question 1
1 / -0

Two mirrors are kept at 60 to each other and a body is placed at middle. Total number of images formed is

A
six

B
four

C
five

D
three

Solution

Number of images = $$\dfrac{360^0}{60^0} - 1$$
= $$6 - 1$$
= 5.
Question 2
1 / -0

Which of the following is not a characteristic of light ?

A
Light travels with $$3 \times 10^{8}\ ms^{-1} $$ speed.

B
Light is an electromagnetic radiation which produces sensation in our eye

C
Light travels on a straight path

D
Light is a mechanical wave

Solution

Light is an electromagnetic radiation which produces sensation in our eye. It travels with a speed of $$ 3 \times 10^{8} \ m/s$$. It always travels in a straight line.
Light waves are not considered as mechanical waves because they don't need medium to travel.
Correct Option is D.
Question 3
1 / -0

Band of colours seen emerging from a prism is called:

A
wavelength

B
Beam

C
Spectrum

D
bandwidth

Solution

Band of seven colours seen emerging from a prism when white light is incident on it is called a spectrum of light.
This splitting occurs because different colours of light bend through different angles with respect to the incident ray, as they pass through a prism.
Question 4
1 / -0

Why does a red coloured object seem to be red?

A
It reflect red colour.

B
It allows red colour to pass through.

C
It scatters red colour.

D
It absorb red colour.

Solution
Question 5
1 / -0

Suppose you are in a dark room with a small window through which a faint light is getting in. Which of the following statements is true?

A
you can see the objects inside the room and objects outside the room

B
you can only see object outside the room but not the objects inside the room

C
you can only see object inside the room but not the objects outside the room

D
you cannot see any objects while inside the room

E
Data Insufficient

Solution

We can see an object if light reflected or emitted by it reaches our eyes. If we are in a dark room, no light will enter into our eyes. Thus, it is not possible for us to see objects in the room. But, objects outside the room may be visible to us. If there is a light present outside the room or an object is emitting its own light, then we can see the objects that are present outside the room.
Question 6
1 / -0

With an object between those, if the angle between two plane mirrors is acute, the number of images formed will be:

A
more than $$3$$

B
less than $$3$$

C
more than $$1$$

D
equal to zero

Solution

If two plane mirrors are at right angles to each other, those form 3 images of an object. ($$n=\dfrac{360}{90}-1=3$$)
Further we increase the angle, i.e, when the angle is obtuse, the number of images become less than 3.
And, if we decrease the angle, i.e., when the angle is acute, the number of images become more than 3.
Question 7
1 / -0

In which of the following conditions diffuse reflection takes place?

A
When a parallel beam of light is reflected by a plane mirror.

B
When a parallel beam of light is reflected by a highly polished metal surface.

C
When a parallel beam of light is reflected by a paper sheet.

D
All of these

Solution

When all the parallel rays reflected from a rough or irregular surface are not parallel, the reflection is known as diffused or irregular or diffuse reflection. Diffuse reflection occurs at rough surfaces like paper.
Question 8
1 / -0

Find the angle of reflection from the given diagram.

A
$${\theta}^0$$

B
$$90-{\theta}^0$$

C
$$45^0$$

D
$$90^0$$

Solution
Question 9
1 / -0

Situation: Two plane mirrors are arranged such as a ray of light incident on the first mirror is reflected towards second mirror and after being reflected from second mirror, the ray emerges parallel to incoming ray. The deviation in the ray is

A
$$0 ^ { \circ }$$

B
$$90 ^ { \circ }$$

C
$$180 ^ { \circ }$$

D
none of these

Solution
Question 10
1 / -0

According to the first law of reflection, which angles will be equal?

A
A=C

B
B=D

C
A=B

D
B=C

Solution

Law of reflection states that angle of incidence and angle of reflection are equal. That is B=C. hence, D is the correct option