Light Test

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Light Test - 33

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Weekly Quiz Competition

Question 1
1 / -0

An incident ray passing through the focus will be reflected :

A
straight away

B
through the pole of the mirror

C
back and passes through the centre of curvature

D
parallel to the principal axis

Solution

An incident ray passing through the focus will move parallel to the principal axis after reflection from spherical mirror.
Question 2
1 / -0

The incident ray, reflected ray and the normal in case of a plane mirror are in the ..............

A
Same plane

B
Different planes

C
Parallel planes

D
None of the above
Solution
According to laws of reflection for a plane mirror.
The incident ray and reflected ray and the normal all lie in the same plane.
The angle of incidence is equal to angle of reflection.
Question 3
1 / -0

When a light ray is reflected repeatedly by a set of parallel plane mirrors, the intensity of light rays decreases after some reflections. This is because of :

A
poor reflection from mirrors

B
absorption of some amount of light by mirrors

C
dispersion of light when the rays travel through the atmosphere

D
scattering of light by the mirrors

Solution

The mirrors used in real life are not ideal hence they absorb some amount of light and the intensity of the light subsequently decreases when it gets repeatedly reflected by set of mirrors.
Question 4
1 / -0

The Braille code used by blind people use dot patterns for words. How many dot patterns or characters are used for this code?

A
52

B
63

C
48

D
26

Solution

Correct answer is (b)
Braille is universally accepted system for writing used by blind people, which uses dot patterns for words and it consists of a code of 63 characters, each made up of one to six raised dots arranged in a six-position matrix. These Braille characters are embossed in lines on paper and read by passing the fingers lightly over the manuscript.

Braille assignments have also been used and created for mathematical and musical notation.
Question 5
1 / -0

When the angle between two plane mirrors is $$30^{\circ}$$, how many multiple images will be formed by the mirrors?

A
11

B
12

C
5

D
13

Solution

$$\text{Formula to be used:}$$ $$n=\dfrac{360^o}{\theta}-1$$, where $$\theta$$ is the angle between the mirrors.,
Here, the angle between two mirrors is $$\theta=30^0$$.
So, number of images formed is $$n=\dfrac{360^o}{30^o}-1=11$$
Question 6
1 / -0

Fill in the blanks:
In our eyes an image of objects we wish to view is made at the _________ .

A
retina

B
pupil

C
iris

D
cornea

Solution

Human eye adjusts its shape so that the image is formed on the retina as shown in the attached diagram.
Question 7
1 / -0

When the distance between the object and the plane mirror increases:

A
the image distance remains same

B
the size of the image will become less than the size of the object

C
the distance between the image and the plane mirror increases

D
the distance between the image and the plane mirror decreases

Solution

For a plane mirror, object distance $$=$$ image distance.
So, if the distance between the object and the plane mirror increases, the distance between the image and the plane mirror also increases.
Question 8
1 / -0

If the angle of incidence is $$50^{\circ}$$, then calculate the angle between the incidence ray and the reflected ray is ?

A
$$50^{\circ}$$

B
$$100^{\circ}$$

C
$$130^{\circ}$$

D
$$80^{\circ}$$

Solution

The angle of incidence, $$\angle ANM= i=50^0$$
By law of reflection $$i=r$$
So, the angle of reflection, $$ \angle MNB = r=i=50^0$$
Angle between the incident and the reflected ray $$=i+r=50^0+50^0=100^0$$.

However, if we were asked the angle between the "direction" of incident ray and reflected ray, then it would be $$\angle CNB$$
$$\angle CNB=180^o-(i+r)=180^o-100^o=80^o$$
Question 9
1 / -0

The light enters our eye through the transparent _________, passes through the _______ and is focused on the _______. The ________ is sensitive to light and sends images to our brain through _________ .

A
cornea, lens, retina, retina, optic nerve

B
retina,cornea, lens, retina, optic nerve

C
retina, cornea, lens, optic nerve ,retina

D
cornea,retina, lens, retina, optic nerve

Solution

Light enters our eye through the cornea, the clear, curved layer in front of the iris and pupil. After passing through the cornea, light travels through the pupil which is surrounded by iris and behind the iris sits the lens which changes the shape and focuses light onto the retina then the photoreceptors in the retina convert the image into electrical signals, which are carried to the brain by the optic nerve.
Question 10
1 / -0

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

A
One

B
Two

C
Less than forty

D
Less than twenty

E
Infinite

Solution

Infinite (very large) numbers of images of the candle will be formed because of multiple reflections between the mirrors.

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Light Test - 33

Result

Light Test - 33

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Rank

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SHARING IS CARING

Question 1

straight away

through the pole of the mirror

back and passes through the centre of curvature

parallel to the principal axis

Solution

Question 2

Same plane

Different planes

Parallel planes

None of the above

Solution

Question 3

poor reflection from mirrors

absorption of some amount of light by mirrors

dispersion of light when the rays travel through the atmosphere

scattering of light by the mirrors

Solution

Question 4

52

63

48

26

Solution

Question 5

11

12

5

13

Solution

Question 6

retina

pupil

iris

cornea

Solution

Question 7

the image distance remains same

the size of the image will become less than the size of the object

the distance between the image and the plane mirror increases

the distance between the image and the plane mirror decreases

Solution

Question 8

$$50^{\circ}$$

$$100^{\circ}$$

$$130^{\circ}$$

$$80^{\circ}$$

Solution

Question 9

cornea, lens, retina, retina, optic nerve

retina,cornea, lens, retina, optic nerve

retina, cornea, lens, optic nerve ,retina

cornea,retina, lens, retina, optic nerve

Solution

Question 10

One

Two

Less than forty

Less than twenty

Infinite

Solution

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