MEDIUM
12th West Bengal Board
IMPORTANT
Earn 100
Where should an object be placed from a convex lens to form an image of the same size? Can it happen in the case of a concave lens?
Important Questions on Refraction at Spherical Surfaces and Spherical Lens
HARD
12th West Bengal Board
IMPORTANT
The image of a candle is formed by a convex lens on a screen. The lower half of the lens is painted black to make it comply opaque. Draw ray diagram to show, the image formation. How this image be different from one obtained, when the lens is not painted black.
MEDIUM
12th West Bengal Board
IMPORTANT
Two thin lenses of power and are in contact. What is the focal length of the combination?
MEDIUM
12th West Bengal Board
IMPORTANT
A converging lens axially in contact with a diverging lens. Both the lenses being of equal focal lengths. What is the focal length of the combination?
EASY
12th West Bengal Board
IMPORTANT
Show that the optical centre of plan convex lens is situated at the pole of the curved surface of the lens.
MEDIUM
12th West Bengal Board
IMPORTANT
The image of a small electric bulb fixed on the wall of a room is to be obtained on the opposite wall away by means of a large convex lens. What is the maximum possible focal length of the lens required for the purpose?
MEDIUM
12th West Bengal Board
IMPORTANT
Explain why does a convex lens behave as a converging lens when immersed in water and as a diverging lens when immersed in carbon disulphide .
MEDIUM
12th West Bengal Board
IMPORTANT
Use the lens equation to deduce algebraically, what you know otherwise from explicit ray diagrams: an object placed within the focus of a convex lens produces a virtual and enlarged image.
MEDIUM
12th West Bengal Board
IMPORTANT
Use the lens equation to deduce algebraically, what you know otherwise from explicit ray diagrams: a concave lens produces a virtual and diminished image independent of the location of the object.
