Image Distance and Object Distance

Q. A real image magnified three times is formed when an object is placed 20 cm from a concave mirror. What is the focal length of the mirror?

1. 20 cm
2. 30 cm
3. 15 cm
4. 10 cm

Q. The linear magnification for a spherical mirror is the ratio of the size of the image to the size of the object, and is denoted by m. Then m is equal to (symbols have their usual meanings)

1. $\frac{u}{u-f}$
2. $\frac{uf}{u-f}$
3. $\frac{f}{u+f}$
4. None of these

Q. Identify the correct position of the image of the Sun formed by the concave mirror.

1. 
2. 
3. 
4. 
5. 

Q. If the radius of curvature of a concave mirror is 20 cm, then its focal length is:

1. 10

Q. In a glass slab, if the angle of incidence and emergence of light is i and e, then:

1. i - e = 0
2. i = 2e
3. i = 0.5e
4. i + e = 90

Q. A real image of half the size is obtained in a concave spherical mirror with a radius of curvature of 40 cm. The distance of the object and that of its image from the mirror will be respectively

1. 15 cm, 30 cm
2. 30 cm, 15 cm
3. 30 cm, 60 cm
4. 60 cm, 30 cm

Q. Which of the following can never be the value of the refractive index of a medium?

1. 2.24
2. 1.87
3. 3.45
4. 0.66

Q. An object is placed at $60cm$ from the pole of a concave mirror whose focal length is $20cm$. Find the distance at which the image is formed.

1. $v=–30cm$
2. $v=–20cm$
3. $v=+30cm$
4. $v=+20cm$