Reflection Test

Result

Reflection Test - 8

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 person is standing in front of a plane mirror.If the mirror recedes with velocity v , the relative speed of person and his image per second is-

A
0

B
v

C
2v

D
v/2

Solution

Distance of Image formed in the mirror is same as the distance of the object form the surface of the mirror.

Thus is distance of object = u

Then distance of image = -u (as the image is formed at other side of the mirror)

Thus distance between image and object = 2u ...(1)

Now if mirroe is receding you/object with speed -v, then distance travelled by mirror in unit time = v units

Thus distance between mirror and object in unit time = u - v

Thus disatnce between object and its image = 2(u-v)....(2)

From equations (1) and (2) distance between image and object is reduced by 2v units in unit time(1 second)

Thus speed of image w.r.t object = 2v
Question 2
1 / -0

Two plane mirrors are placed perpendicular to each other. A ray strikes one mirror and, after reflection, falls on the second mirror. The ray, after reflection from the second mirror, will emerge:

A
perpendicular to the original ray

B
parallel to the original ray

C
at 45^∘ to the original ray

D
at any angle to the original ray

Solution

Let ray strikes the vertical mirror by angle of incidence θ. Then by joining the perpendiculars of two mirrors it is clear from the diagram that angle of incidence at horizontal mirror is (90−θ).

∴ reflected ray from horizontal mirror makes angle θ with the horizontal mirror also incident ray at vertical mirror makes angle θ with horizontal axis.

∴ reflected ray is parallel to the original ray.

This is true for two perpendicular mirrors fixed at any positions.
Question 3
1 / -0

A person is in a room whose ceiling and two adjacent walls are mirrors. How many images are formed :

A
5

B
6

C
7

D
8

Solution

The wall will act as two mirrors inclined to each other at 90° and so will form 360°/90° − 1 = 3 images of the person.

Three images by walls now these images with object (person) will act as objects for the ceiling mirror and so ceiling will form 4 images. Hence total no. of images formed = 3 + 4 = 7
Question 4
1 / -0

Number of images observable between two parallel mirrors is

A
2

B
4

C
6

D
infinite

Solution

Number of images observable between two parallel mirrors is infinite bcoz each mirror reflects both mirrors
Question 5
1 / -0

An object is placed symmetrically between the two plane mirrors inclined at angle of 30^o. Then the total number of images formed is:

A
12

B
2

C
11

D
15

Solution

= 12 − 1

= 11
Question 6
1 / -0

Images of an object that is equidistant from the two plane mirrors whose reflecting surfaces make an angle of 90^∘ with one another lie on a/an

A
Straight line

B
parabola

C
Circle

D
Ellipse

Solution

By applying the concept of object distance = image distance from the plane mirror, we can see that 3 images and the object are symmetrical w.r.t intersection of the mirrors M₁ and M₂. Therefore, all the 3 images lie on a circle with centre at intersection of the mirrors.
Question 7
1 / -0

Two plane mirrors are inclined to one another at an angle of 40^∘. A point object is placed in between them. The number of images formed due to reflection at both mirrors is

A
Infinite

B
9

C
8

D
6

Solution
Question 8
1 / -0

What should be the angle between two plane mirrors so that whatever be the angle of incidence, the incident ray and the reflected ray from the two mirrors be parallel to each other

A
60^∘

B
90^∘

C
120^∘

D
175^∘

Solution

Incident ray and finally reflected ray are parallel to each other means δ=180∘

From δ=360−2θ⇒180=360−2θ⇒θ=90∘
Question 9
1 / -0

A ray gets successively reflection from two mirrors inclined at an angle of 40^o. If the angle of incidence on the first mirror is 30^o then the net deviation of this ray after two reflections :

A
40^o

B
280^o

C
180^o

D
240^o

Solution

Angle of deviation in case of double reflection is given as

δ = 360° − 2θ = 360° − 2(40°) = 360° − 80° = 280°
Question 10
1 / -0

The focal length of a spherical mirror is ____ its radius of curvature.

A
half

B
twice

C
thrice

D
equal to

Solution

Focal length of spherical mirror is half the radius of curvature i.e f = R/2