Light Test

Result

Light Test - 35

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
1 / -0

If the glancing angle of incidence is 50$$^o$$, then calculate the angle between the incident ray and the reflected ray:

A
$$50^o$$

B
$$100^o$$

C
$$130^o$$

D
$$80^o$$

Solution

The glancing angle of incidence $$=50^0$$.
So, the angle of incidence $$i=90^0-50^0=40^0$$
And, the angle of reflection, $$r=40^0$$
Angle between incident and reflected rays $$=i+r=40^0+40^0=80^0$$
Question 2
1 / -0

Dispersion of white light into its constituent colours occurs during

A
reflection at a plane mirror

B
reflection at a concave mirror.

C
internal reflection inside a spherical drop of water

D
refraction at the boundary of a transparent medium.

Solution

Upon entry of white light at the first boundary of a triangular prism, there will be a slight separation of the white light into the component colours of the spectrum. Upon exiting the triangular prism at the second boundary, the separation becomes even greater and ROYGBIV is observed in its spectrum. Hence, Dispersion of white light into its constituent colours occurs during refraction at the boundary of a transparent medium.
Question 3
1 / -0

Two mirrors are inclined at an angle of $$45^0$$, an object is placed between them. Then number of images formed will be:

A
6

B
7

C
5

D
9

Solution

Angle between the mirrors$$=\theta=45^0$$
So, number of images, $$n=\dfrac{360}{45}-1=7$$
Question 4
1 / -0

Two mirrors are inclined at an angle $$120^0$$, an object is placed asymmetrically between them. Then number of images formed will be:

A
1

B
2

C
3

D
4
Question 5
1 / -0

Find number of images formed according to given case

A
8, 9

B
9, 8

C
9, 9

D
8, 8

Solution

If the image of an object is viewed in two plane mirrors that are inclined to each other more than one image is formed. The number of images depends on the angle between the two mirrors.
The number of images formed in two plane mirrors inclined at an angle A to each other is given by the below formula.Number of images n= 360/A - 1
The number of images formed n=(360/A)-1, if (360/A) is even integer.If (360/A) is odd integer, the number of images formed n=(360/A)-1 when the object is kept symmetrically, and n=(360/A) when object is kept asymmetrically.
If (360/A) is a fraction, the number of images formed is equal to its integral part.
As the angle gets smaller (down to 0 degrees when the mirrors are facing each other and parallel) the smaller the angle the greater the number of images.
Here, the angle A between the mirrors is 40 degrees.
Case (a): The object is symmetrically placed.
The number of images formed = (360/40)-1, we get 8 images.
Case (b): The object is asymmetrically placed.
The number of images formed = (360/40), we get 9 images.
Hence, the number of images formed are 8 and 9 respectively.
Question 6
1 / -0

To get 9 multiple images of an object, the angle between two plane mirrors should be:

A
60$$^0$$

B
36$$^0$$

C
50$$^0$$

D
90$$^0$$

Solution

$$n=9$$. Let the angle between two mirrors be $$\theta$$.

So, $$9=\dfrac{360^0}{\theta}-1$$

or, $$10\theta = 360^0$$

or, $$\theta=36^0$$
Question 7
1 / -0

Which of the following correctly represents the relation between angles of incidence and reflection in accordance with the laws of reflection?

A

B

C

D

Solution

According to the law of reflection, angle of incidence ($$i$$) is equal to the angle of reflection ($$r$$).
$$i=r$$
So, $$i$$ vs $$r$$ graph will be a straight line passing through the origin and equally inclined at both the axes.
Question 8
1 / -0

An incident ray makes an angle of $${ 90 }^{ \circ }$$with the mirror surface. The angle of reflection for this ray is:

A
$${ 90 }^{ \circ }$$

B
$${ 0 }^{ \circ }$$

C
$${ 30 }^{ \circ }$$

D
$${ 45 }^{ \circ }$$

Solution

The angle of incidence is measured with respect to the normal drawn at the point of incidence.
The incident ray makes an angle of $$90^0$$ with the mirror surface.
So, angle of incidence $$=(90^0 - 90^0)=0^0$$
According to the laws of reflection, the angle of incidence is equal to the angle of reflection.
The angle of reflection $$=0^0$$.
Question 9
1 / -0

Two plane mirrors are set at right angle and a flower is placed in between the mirrors. The number of images of the flower which will be seen is:

A
One

B
Two

C
Three

D
Four

Solution

Images $$= \displaystyle\frac{360}{\theta} - 1$$
$$= \displaystyle\frac{360}{90} - 1 = 3$$
Question 10
1 / -0

A planet shines because it reflects the light of the

A
sun

B
other planets

C
milky way

D
pole star

Solution

All the planets and moon shines at night only because they reflect the light from the sun.