Position and Size of Image Formed

Q.

The size of an image of an object by a mirror having a focal length of 20 cm is observed to be reduced to $\frac{1}{3}rd$ of its size. At what distance the object has been placed from the mirror? What is the nature of the image and the mirror?

Q.

At what distance from a concave mirror of focal length 25 cm should an object be placed ? so that the size of image is equal to the size of object ___

Q. The nature of the image formed by concave mirror when the object is placed between the focus and centre of curvature of the mirror observed by us is

1. Real, inverted and diminished
2. Real, inverted and enlarged
3. Virtual, upright and enlarged
4. Virtual, erect and smaller in size

Q.

An object of height 4 cm is placed at a distance of 15 cm in front of a concave lens of power -10D. Find the size of the image.

Q.

Why is the image inverted in a concave mirror?

Q. An object is placed at a distance of 10 cm from a convex lens of power 5D.The position of the image is ?

Q.

An object is placed at 25 cm from a convex mirror. Its image is formed 15 cm from the mirror. Find the focal length of the mirror.

Q. What will happen to a ray passing through focus of a concave mirror after reflection?

Q.

A ray of light passes through the focus of the mirror. After reflection, it

1. goes through the pole of the mirror.

2. becomes parallel to the principal axis.

3. goes through the centre of curvature.

4. Passes between the pole and focus of the mirror.

Q. Draw the ray diagram. [2 Mark]

Q.

Find the focal length of the given mirror.

1. – 30 cm
2. – 20 cm
3. + 20 cm
4. + 30 cm

Q.

How will the magnitude of magnification change if an object placed at center of curvature is moved towards focus in concave mirror?

1. It decreases

2. It increases

3. It remains constant

4. It becomes equal to infinity

Q. A concave mirror is lying on a table with its reflecting surface facing upwards and pole touching the table. The mirror is rotated about its principal axis in clockwise direction. The image of a person looking straight into it

1. Rotates in clockwise direction
2. Rotates in anti-clockwise direction
3. Is inverted
4. Does not rotate

Q. A concave mirror produces three times magnified (enlarged) real image of an object placed at 10 cm in front of it. Where is the image located?

Q. Find the distance between two possible positions of a real object in front of a convex lens of focal length 15 cm such that the size of the image is double the size of the object.

1. 25 cm
2. 15 cm
3. 20 cm
4. 30 cm

Q. A dentist uses a spherical mirror to view the tooth of a patient. The required image is to be upright and four times the size of the tooth. Calculate the magnitude of the focal length of the mirror to be used, if the mirror is to be held 1.50 cm from the tooth.

1. - 1 cm
2. - 2 cm
3. - 2.25 cm
4. - 1.25 cm

Q. Question 12
An object is placed at a distance of 10 cm from a convex mirror of focal length 15 cm. Find the position and nature of the image.

Q. An object of 5.0 cm height is placed at a distance of 20 cm in front of a concave mirror of radius of curvature 30 cm. Find the position of the image, its nature and size.

Q.

A 2 cm high object is placed at a distance of 20 cm from a concave mirror. A real image is formed 40 cm from the mirror. Calculate the focal length of the mirror and the size of the image. [3 MARKS]

Q.

State the relation between object distance, image distance and focal length of a spherical mirror.

Q.

Question 2
A 10 mm long awl pin is placed vertically in front of a concave mirror. A 5 mm long image of the awl pin is formed at 30 cm in front of the mirror. The focal length of this mirror is

(a) -30 cm
(b) -20 cm
(c) -40 cm
(d) -60 cm

Q.

When an object of height 1 cm is kept at a distance of 4 cm from a concave mirror, its upright image of height 1.5 cm is formed at a distance of 6 cm behind the mirror. Calculate the focal length of the mirror.

Q.

Explain why array passing through centre of curvature of a concave mirror reflected back to its same path

Q. What is the separation between a concave mirror and paper sheet having a bright sharp spot of light(sunlight).

Q.

State the principles of image formation in the case Of a spherical mirror. Use this principle to describe with the help of a diagram the nature, size, and position of the image formed when an object is placed beyond the centre Of curvature of a concave mirror.

Q. Match the formulae with their names

1. $\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$
2. $\frac{1}{v}-\frac{1}{u}=\frac{1}{f}$
3. $\frac{1}{f}$
4. $h_i/h_o$

Q.

Question 10
An object 5 cm in length is held 25 cm away from a converging lens of focal length 10 cm. Draw the ray diagram and find the position, size and the nature of the image formed.

Q. An object is placed at a distance of 20 cm in front of a concave mirror of focal length 10 cm. Calculate the image distance (in cm).

1. -20

Q. An object is placed at a distance of 30 cm in front of an unknown mirror. The mirror forms an image at 20 cm behind itself. Find out the focal length and type of the mirror.

1. 60 cm, convex mirror
2. 60 cm, concave mirror
3. 20 cm, concave mirror
4. 20 cm, convex mirror

Q. Match the incident rays with the reflected rays after they reflect off a spherical mirror.

1. At focus
2. Rays retrace
3. To infinity