Image Formation in Concave Mirror

Q.

The focal length of concave mirror is 20 cm. where should an object be placed to get an image magnified twice?

Q. An object is placed at a distance of $40cm$ from a concave mirror of focal length $15cm$. If the object is displaced through a distance of $20cm$ towards the mirror, the displacement of the image will be

1. $36cm$ away from the mirror
2. $30cm$ away from the mirror
3. $30cm$ towards the mirror
4. $36cm$ towards the mirror

Q. An object is placed at a distance of $30\text{cm}$ from a concave mirror and its real image is formed at a distance of $30\text{cm}$ from the mirror. The focal length of the mirror is

1. $20\text{cm}$
2. $15\text{cm}$
3. $45\text{cm}$
4. $30\text{cm}$

Q.

The focal length of a concave mirror is 50 cm. Where an object be placed so that its image is two times and inverted?

1. 63 cm
2. 75 cm

3. 72 cm

4. 50 cm

Q. A candle flame 3 cm is placed at distance of 3 m from a wall. How far from wall must a concave mirror be placed in order that it may form an image of flame 9 cm high on the wall

1. 225 cm
2. 300 cm
3. 650 cm
4. 450 cm

Q. An object of length 2.5 cm is placed at a distance of 1.5 f from a concave mirror where f is the magnitude of the focal length of the mirror. The length of the object is perpendicular to the principal axis. The length of the image is

1. 5 cm, erect
2. 15 cm, erect
3. 10 cm, erect
4. 5 cm, inverted

Q.

Two objects A and B when placed one after another infront of a concave mirror of focal length 10 cm form images of same size. Size of object A is four times that of B. If object A is placed at a distance of 50 cm from the mirror, what should be the distance of B from the mirror?

1. 10 cm
2. 20 cm
3. 30 cm
4. 40 cm

Q. A concave mirror of focal length 100 cm is used to obtain the image of the sun which subtends an angle of 30'. The diameter of the image of the sun will be

1. 1.74 cm
2. 0.87 cm
3. 0.435 cm
4. 100 cm

Q. Choose the correct option.
Assertion: A person cannot see his inverted image in a concave mirror unless he is situated beyond the centre of curvature of the mirror.
Reason: In a concave mirror, image formed is real provided the object is situated between focal point and pole.

1. Both assertion and reason are true and reason is the correct explanation of the assertion.
2. Both assertion and reason are true and reason is not the correct explanation of the assertion.
3. Assertion is true, but reason is false.
4. Both assertion and reason are false.

Q. A concave mirror of focal length 15 cm forms an image having twice the linear dimensions of the object. The position of the object when the image is virtual will be

1. 30 cm
2. 45 cm
3. 22.5 cm
4. 7.5 cm

Q. The focal length of a concave mirror is $30cm$. Find the distance of the object in front of the mirror, so that the image is three times the size of the object.

1. $40cm,20cm$
2. $60cm,80cm$
3. $30cm,50cm$
4. $25cm,15cm$

Q. An infinitely long rod lies along the axis of a concave mirror of focal length f. The near end of the rod is at a distance u > f from the mirror. Its image will have a length

1. $\frac{uf}{u-f}$
2. $\frac{uf}{u+f}$
3. $\frac{f^2}{u+f}$
4. $\frac{f^2}{u-f}$

Q. A concave mirror is used to focus the image of a flower on a nearby well 120cm from the flower. If a lateral magnification of 16 is desired, the distance of the flower from the mirror should be

1. 12 cm
2. 80 cm
3. 120 cm
4. 8 cm

Q. A ray of light is incident on one of the faces of the prism with an angle 40 with the surface. The angle of the prism is 60. The emergent ray is deviated through an angle 38. The angle of emergence is. A 38. B 48. C 52 D 58. Kindly explain the solution.

Q. Which of the following options represents incorrect ray diagram for a concave mirror?

1. 
2. 
3. 
4. 

Q. An object 2.5 cm high is placed at a distance of 10 cm from a concave mirror of radius of curvature 30 cm The size of the image is

1. 5.6 cm
2. 7.5 cm
3. 9.2 cm
4. 10.5 cm

Q. A ray incident at an angle ${53}^{\circ }$ on a prism and emerges at an angle of ${37}^{\circ }$ as shown in figure. If the angle of incidence is made ${50}^{\circ }$ then possible value of the angle of emergence is

1. ${35}^{\circ }$
2. ${38}^{\circ }$
3. ${42}^{\circ }$
4. ${40}^{\circ }$

Q.

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

1. 0.11cm
2. 0.50cm

3. 0.55cm

4. 0.60cm

Q.
An isosceles prism has one of the refracting surfaces silvered. A ray of light is incident normally on the refracting face AB. After two reflections ray emerges from base BC normally. Then angle of prism is

1. ${72}^{\circ }$
2. ${56}^{\circ }$
3. ${36}^{\circ }$
4. ${40}^{\circ }$

Q. A thin rod of length $\frac{f}{3}$ lies along the axis of a concave mirror of focal length f. One end of its magnified image touches an end of the rod. The length of the image is

1. f
2. 2f
3. $\frac{f}{2}$
4. $\frac{f}{4}$

Q.

A ray of light incident at the pole of a spherical mirror is reflected along a path, making the same angle with the principal axis, as the incident ray does.

1. True
2. False

Q. An object is placed $40\text{cm}$ infront of a concave mirror of focal length $20\text{cm}$. The image formed is

1. real, inverted and of same size
2. real, inverted and smaller in size
3. virtual, erect and larger in size
4. virtual, erect and smaller in size

Q. 29.An object is approaching a concave mirror at constant speed. Comment on the speed of the image formed

Q. A ray of light is incident at an angle of incidence $i$ on one surface of a thin prism $($with angle of prism $A$$)$ and emerges normally from the other face. If the refractive index of the prism is $n$. then the angle of incidence is nearly equal to :

1. $nA$
2. $\frac{2A}{n}$
3. $\frac{A}{2n}$
4. $\frac{nA}{2}$

Q.

For a concave mirror, if real image is formed the graph between is of the form

1. 
2. 
3. 
4. 

Q. The figure shows two incident rays $A$ and $B$ being reflected by a mirror as $A^{\prime }$ and $B^{\prime }$. The mirror is a

1. plane mirror
2. convex mirror
3. concave mirror
4. convex mirror or a concave mirror

Q. Two identical prisms 1 and 2, each will angles of ${30}^{\circ },{60}^{\circ }$ and ${90}^{\circ }$ are placed in contact as shown in figure. A ray of light passed through the combination in the position of minimum deviation and suffers a deviation of ${30}^{\circ }$. If the prism 2 is removed, then the angle of deviation of the same ray is

1. Equal to ${15}^{\circ }$
2. Smaller than ${30}^{\circ }$
3. Equal to ${30}^{\circ }$
4. More than ${15}^{\circ }$

Q. An object is placed at a distance of 60 cm in front of a concave mirror of radius of curvature 40 cm. If the height of the object is 10 cm, find the location and height of the image.

1. 30 cm in front of the mirror, 5cm
2. 30 cm behind the mirror, 10 cm
3. 30 cm in front of the mirror, 20 cm
4. 60 cm behind the mirror, 5cm

Q. The direction of a ray of light incident on a concave mirror is shown by $PQ$ while direction in which the ray will travel after reflection is shown by four rays marked as $1,2,3$ and $4$ as shown in the figure. Which ray among the four rays correctly shows the direction of the reflected ray?
$[C$ is the centre of curvature and $F$ is focus$]$

1. $1$
2. $2$
3. $3$
4. $4$

Q. Find the angle of incidence of ray for which after reflection, it passes through pole of concave mirror.

1. ${90}^{\circ }$
2. ${60}^{\circ }$
3. ${75}^{\circ }$
4. ${30}^{\circ }$