EASY
12th West Bengal Board
IMPORTANT
Earn 100

A concave lens of focal length 24 cm is kept in front of a concave mirror at a distance of 20 cm on the axis. If a pin  is kept at a distance of 36 cm in front of the lens, the inverted image of the pin formed by the combination of lens and mirror coincides with the object. Calculate the focal length of the mirror.

 

Important Questions on Refraction at Spherical Surfaces and Spherical Lens

EASY
12th West Bengal Board
IMPORTANT
A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 14 - Refraction at Spherical Surfaces and Spherical Lens>EXERCISE 14>Q 17
A convex lens B of focal length 20 cm is placed at a distance of 30 cm to the right of an identical lens A. A point object is placed at a distance of 30 cm to the left of A on the common axis of the two lenses. Where should a convex mirror of radius of curvature 7 cm be placed so that the final image coincides with the object.
HARD
12th West Bengal Board
IMPORTANT
A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 14 - Refraction at Spherical Surfaces and Spherical Lens>EXERCISE 14>Q 18
When a small object is placed at A on the axis of a convex lens of focal length f, the image is erect. When the object is moved to B, the image is inverted but of the same size as before. If m be the magnification, show that AB=2fm.
MEDIUM
12th West Bengal Board
IMPORTANT
A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 14 - Refraction at Spherical Surfaces and Spherical Lens>EXERCISE 14>Q 19
An object is placed in front of a concave lens at a distance equal to its focal length. A concave mirror of focal length 25 cm is placed 40 cm behind the lens and a real image is observed to be coincident with the object. Find the focal length of the lens. 
EASY
12th West Bengal Board
IMPORTANT
A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 14 - Refraction at Spherical Surfaces and Spherical Lens>EXERCISE 14>Q 20
The image of a square hole on a screen illuminated by light is obtained on another screen with the help of a converging lens. The distance of the illuminated square from the lens is 40 cm. The area of the image is 9 times that of the square hole. Calculate the position of the image and the focal length of the lens. 
HARD
12th West Bengal Board
IMPORTANT
A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 14 - Refraction at Spherical Surfaces and Spherical Lens>EXERCISE 14>Q 21
A convex lens is placed between an object and a screen. For two positions of the lens, real images are produced on the screen. If the lengths of the two images be I1 and I2 and that of the object be O, prove that O=I1I2
EASY
12th West Bengal Board
IMPORTANT
A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 14 - Refraction at Spherical Surfaces and Spherical Lens>EXERCISE 14>Q 22
When an object is placed 20 cm away in front of a convex lens, its 3 times magnified inverted image is formed. In which direction and how much should the lens be shifted in front of the object so that its 3 times magnified erect image may be seen.  
EASY
12th West Bengal Board
IMPORTANT
A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 14 - Refraction at Spherical Surfaces and Spherical Lens>EXERCISE 14>Q 23

A thin Plano-convex lens of focal length $f$ is split into two halves; one of the halves is shifted along the optical axis [Fig. 14.71]. The separation between object and image is $1.8 \mathrm{~m}$. The magnification of the image formed by one of the half-lenses is 2. Find the focal length of the lens and the separation between the two halves. Draw the ray diagram for image formation.

Question Image

HARD
12th West Bengal Board
IMPORTANT
A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 14 - Refraction at Spherical Surfaces and Spherical Lens>EXERCISE 14>Q 24
A pin is placed 10 cm in front of a convex lens of focal length 20 cm and made of a material of refractive index 1.5. The surface of the lens farther away from the pin is silvered and has a radius of curvature of 22 cm. Determine the position of the final image. Is the image real or virtual?