Reflection Test

Result

Reflection Test - 9

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Question 1
1 / -0

If a spherical mirror is immersed in a liquid, its focal length will:

A
Increase

B
Decrease

C
Remain unchanged

D
Depend on the nature of liquid

Solution

Focal length is the property of the spherical mirror. So, it does not changes when immersed in liquid.
Question 2
1 / -0

An object is placed at a distance of 40 cm in front of a concave mirror of focal length 20 cm. The image produced is:

A
real, inverted and smaller in size

B
real, inverted, and of same size

C
real and erect

D
virtual and inverted

Solution

Object distance, u = −40cm

Focal length, f = −20cm

According to mirror formula,

Negative sign shows that image is infront of concave mirror.

The image is real.

The image is of the same size and inverted.
Question 3
1 / -0

An object 5 cm tall is placed 1 m from a concave spherical mirror which has a radius of curvature of 20 cm. The size of the image is:

A
0.11cm

B
0.50cm

C
0.55cm

D
0.60cm

Solution

Object distance, u=−1 m

Focal length, f=−10 cm

Using mirror formula,
Question 4
1 / -0

Sun subtends an angle of 0.5^o at the pole of a concave mirror of radius of curvature 15 m. The diameter of the image of the sun formed by the mirror is

A
8.55cm

B
7.55cm

C
6.55cm

D
5.55cm

Solution
Question 5
1 / -0

The focal length of a concave mirror is 12 cm. Where should an object of length 4 cm be placed, so that a real image of 1 cm length is formed?

A
48 cm

B
3 cm

C
60 cm

D
15 cm

Solution

Given that,

Focal length of a concave mirror f = 12cm

Object length h = 4

Real image length h′=1cm

We know that,
Question 6
1 / -0

The focal length of a concave mirror is 20cm. Determine where an object must be placed to form an image magnified two times when the image is real

A
30 cm from the mirror

B
10 cm from the mirror

C
20 cm from the mirror

D
15 cm from the mirror

Solution
Question 7
1 / -0

Given a point source of light, which of the following can produce a parallel beam of light

A
Convex mirror

B
Concave mirror

C
Concave lens

D
Two plane mirrors inclined at an angle of 90⁰

Solution
Question 8
1 / -0

A convex mirror is used to form an image of a real object. Then mark the wrong statement.

A
The image lies between the pole and focus

B
The image is diminished in size

C
The image is erect

D
The image is real

Solution

In case of a real object, a convex mirror will always form a diminished, virtual and erect image which lies between focus and pole.
Question 9
1 / -0

The largest distance of the image of a real object from a convex mirror of focal length 20 cm can be

A
20 cm

B
infinite

C
10 cm

D
depends on the position of the object

Solution

We are given that:

Focal length = 20 cm

In a convex mirror image is formed between focal length and mirror.

So the maximum distance is f i.e. focal length of the mirror.

Now

f = 20 / 2 = 10 cm

Thus the largest distance of an image from a convex mirror is 10 cm.
Question 10
1 / -0

An object is placed at a distance of 25cm from the pole of a convex mirror and a plane mirror is set so that the virtual images formed by two mirrors do not have any parallax. The plane mirror is 20cm from the object. The focal length of the mirror is

A
37.5 cm

B
-7.5 cm

C
-37.5 cm

D
+75 cm

Solution

For plane mirror, image is formed 20cm behind it as the object is 20cm in front of it. For convex mirror, Plane Mirror,