Light Test

Result

Light Test - 28

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

A ______ is an instrument used for observing objects from a hidden position.

A
Telescope

B
Microscope

C
Periscope

D
Kaleidoscope

Solution

A Periscope is an instrument used for observing objects from a hidden position.
Question 2
1 / -0

Which of the following are not non-luminous objects ?

A
Moon

B
Planets

C
Sun

D
Earth

Solution

Objects which do not emit light on their own are called $$ \bf{non-luminous} $$ objects.
Objects that give out or emit light of their own are called as $$ \bf{luminous\ objects} $$.

Sun is a source of light and thus, gives out or emits light of it's own and hence, is a luminous object.
Moon, planets and Earth are non-luminous objects because they do not emit light of their own and glow by reflecting the light of the sun.

Hence, the correct answer is OPTION C.
Question 3
1 / -0

This is a representation of:

A
Irregular reflection from a smooth surface

B
Regular reflection from a rough surface

C
Irregular reflection from a rough surface

D
Regular reflection from a smooth surface

Solution

When all the parallel rays reflected from a rough or irregular surface are not parallel, the reflection is known as diffused or irregular reflection. The diffused reflection is not due to the failure of the laws of reflection. It is caused by the irregularities in the reflecting surface, like that of a cardboard.
Question 4
1 / -0

The line PO is called the _______.

A
Reflected ray

B
Incident ray

C
Normal

D
Refracted ray

Solution

An incident ray is a ray of light that strikes a surface.
Hence the line PO is called the incident ray
Question 5
1 / -0

The line OQ is called the :

A
reflected ray

B
incident ray

C
normal

D
refracted ray

Solution

The line OQ is called the reflected ray because incident PO ray is reflected by mirror and goes along OQ.
Question 6
1 / -0

It is desired to photograph the image of an object placed at a distance of $$3$$ m from a plane mirror. The camera, which is at a distance of $$4.5$$ m from the mirror should be focused for a distance of :

A
$$3 m$$

B
$$4.5 m$$

C
$$6 m$$

D
$$7.5 m$$

Solution

The distance between the object and the mirror is $$ 3 m$$, i.e., $$d_1 = 3 m$$,

Hence image distance also equals $$d_1 = 3 m$$

Also, the distance between the mirror and the camera is $$ 4.5 m$$, i.e., $$d_2 = 4.5 m $$ .

Hence the focus of the camera,
$$ f = d_1 + d_2 = 3 + 4.5 = 7.5 m$$
Question 7
1 / -0

A plane mirror reflects a beam of light to form a real image. The incident beam is :

A
parallel

B
convergent

C
divergent

D
any one of the above

Solution

A convergent light beam can do this.
So the answer is "convergent".
You should be able to show this by drawing a "ray diagram" for the light beam. The reflected rays converge and that's what's needed to produce a real image.

A "real object" always produces a "virtual image" in a plane mirror. That's because the reflected rays diverge.
Interestingly, a plane mirror can form a real image if the object itself is virtual.
i.e. rays are convergent.
Question 8
1 / -0

A mirror is inclined at an angle $$\theta $$ with the horizontal. If a ray of light is incident on the mirror at an angle $$\theta $$, then the reflected ray makes the following angle with the horizontal :

A
$$\theta $$

B
$$2\theta $$

C
$$\dfrac{\theta }{2}$$

D
$$90^{\circ}$$

Solution

$$OA$$ & $$OB$$ are two mirrors inclined at an angle $$\theta$$.
$$\overrightarrow{PQ}$$ is the incident ray
$$\overrightarrow{QR}$$ is the reflected ray
$$XY$$ is the normal on $$OA$$ mirror.
So, $$\angle PQX = \theta = \angle XQR$$
$$QR$$ is traced back to meet mirror $$OB$$ at $$S$$.
So, $$\angle$$ $$RQA$$ $$= 90 - \theta$$
$$\therefore \angle OQS = 90 - \theta$$
in triangle $$\Delta OQS, \theta + 90^{\circ}-\theta + \angle O S Q = 180^{\circ}$$
$$\angle OSQ = 90^{\circ}$$
So, reflected ray makes an angle $$90^{\circ}$$ with the horizontal.
Question 9
1 / -0

The angle of reflection is given by the angle :

A
NOQ

B
QOB

C
PON

D
AOP

Solution

The angle between the reflected ray and the normal drawn at the point of incidence to a reflecting surface is known as the angle of reflection.

In the given figure, angle NOQ is the angle of reflection.
Question 10
1 / -0

When an object is placed between two parallel mirrors, then number of images formed is :

A
2

B
4

C
8

D
Infinite

Solution

Number of images formed in two parallel mirror are infinite because an image formed by one mirror can act as an object for the second mirror. And every image formed by the second mirror can act as an object for the first mirror. This image formation will continue for both the mirrors.