Mirror Formula

Q.

What type of image is formed on a cinema screen?

Q. How far from a lamp must a concave mirror of focal length 3m be placed in order to throw its image on the screen 8m from the lamp ?

Q.

An object 20 cm from a spherical mirror gives rise to a virtual image 15 cm behind the mirror. Determine the magnification of the image and the type of mirror used.

Q. Assertion (A): The magnification of a convex mirror is always positive and less than unity.

Reason (R): The image formed in a convex mirror is always virtual, erect and diminished in nature.

Then, which of the following statements is correct?

1. Both A and R are true, and R is not the correct explanation of A.
2. Both A and R are true, and R is the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Q. The nature of the image of a candle flame located 40 cm away from a concave mirror is real, inverted, and magnified four times. What is the radius of curvature of the mirror?

1. 32 cm
2. 64 cm
3. 48 cm
4. 80 cm

Q. The image of a point object kept on the principal axis of a concave mirror of radius of curvature $R=40cm$ is real, inverted and magnified. If the difference in distance between image and object is 30 cm, as per sign convention the object distance (u) will be:

1. $u=30cm$
2. $u=-30cm$
3. $u=60cm$
4. $u=-60cm$

Q.

A person 5 m in front of a plane mirror seems to be ________ m away from his image in the mirror.

1. 12 m
2. 10 m
3. 15 m
4. 5 m

Q. An object is placed at 60 m in front of a concave mirror. If its radius of curvature is 40 m, then the image distance is equal to _____ m.

1. -30
2. 30
3. 20
4. -20

Q.

Nature of the image is not affected by the position of object in a

1. plane mirror.

2. concave mirror.

3. convex mirror.

4. none of these.

Q. the distance between a real object of magnification 1 formed by a concave mirror of focal length f is

Q. A triangular shaped object is placed in front of a concave mirror as shown in the figure. Choose the approximate shape of image formed.

1. 
2. 
3. 
4. 

Q.

Find out the image position formed by concave mirror, considering the image formed by plane mirror as an object for concave mirror.

1. $20\text{cm}$, from the pole
2. $30\text{cm}$, from the pole
3. $40\text{cm}$, from the pole
4. $60\text{cm}$, from the pole

Q.

A person sees his virtual image by holding a mirror very close to the face.

When he moves the mirror away from his face, the image becomes inverted.

What type of mirror he is using

1. Concave mirror

2. Plane mirror

3. Convex mirror

4. None of these

Q. Why concave mirror forms a real and inverted image of an object placed on focus.Why not virtual and erect?

Q. 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

1. $-30$ cm
2. $-20$ cm
3. $-40$ cm
4. $-60$ cm

Q.

A boy with a mouth 5 cm wide stands 2 cm from a plane mirror. Where is his image and how wide is the image of the mouth:

Q. DO MIRRORS HAVE POWER

Q. A dentist uses a small concave mirror of focal length 3 cm and holds it at a distance of 2 cm from a tooth. Find out the magnification of the image formed.

Q. An object of size $50\text{cm}$ is placed $20\text{cm}$ in front of a spherical mirror and its image of size $25\text{cm}$ is formed above the principal axis. Find the focal length as per sign convention and the type of spherical mirror used here?

1. $-25\text{cm}$, concave mirror
2. $-20\text{cm}$, concave mirror
3. $+25\text{cm}$, convex mirror
4. $+20\text{cm}$, convex mirror

Q. Which of the following is not the characteristics of an image formed by a convex mirror?

1. Image lies between pole and focus.
2. Image is diminished.
3. Image is virtual.
4. Image is real.

Q. The image of a point object kept on the principal axis of a concave mirror of radius of curvature $R=40cm$ is real, inverted and magnified. If the difference in distance between image and object is 30 cm, as per sign convention the object distance (u) will be:

1. $u=30cm$
2. $u=-30cm$
3. $u=60cm$
4. $u=-60cm$

Q. A boy is observing his image in a plane mirror. The distance between the mirror and his image is 6 m. If he moves 2 m towards the mirror, then the distance between the boy and his image will be:

1. 8 m
2. 6 m
3. 4 m
4. 2 m

Q. Find the approximate diameter of the image of the moon formed by a spherical concave mirror of focal length 7.6 m. The diameter of the moon is 3450 km and the dis†an ce between the earth and the moon is 3.8 × 10(power 5 )^{} km.

Q. Pl show the area of aperture in sperical mirror. What is meant by intensity of image is proportional to area of aperture

Q. Spherical mirror with reflecting surface curved inwards is called

1. convex mirror
2. concave mirror
3. curved mirror
4. None of these

Q. If aperture of a spherical mirror is increased by 50% find percentage increase in intensity of image

Q. When Arun is at some distance, his image is formed at a distance of 60 cm towards left. Then he starts walking towards the mirror at a speed of 1 cm/s. Find the position of the image formed after 5 seconds.

1. 25 cm
2. 50 cm
3. 100 cm
4. 75 cm

Q.

An object is placed at a distance of 10 $cm$from a concave mirror of radius of curvature 0.6 $m$. Which of the following statement is incorrect?

1. The image is formed at a distance of 15 $cm$ from the mirror.

2. The image formed is real.

3. The image is 1.5 times the size of the object.

4. The image formed is virtual and erect.

Q. No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be:

1. Plane mirror
2. (a) and (c) above.
3. Convex mirror
4. Concave mirror

Q.

If the image formed by a concave mirror is virtual, erect and magnified, then the object is placed:

1. Between the pole of the mirror and the focus

2. Beyond the centre of curvature

3. At the centre of curvature

4. The nature of the image does not depend on the position of the object