Advertisements
Advertisements
Question
An optical device has been given to a student and he determines its focal length by focusing the image of the sun on a screen placed 24 cm from the device on the same side as the sun. Select the correct statement about the device.
(A) Convex mirror of focal length 12 cm
(B) Convex lens of focal length 24 cm
(C) Concave mirror of focal length 24 cm
(D) Convex lens of focal length 12 cm
Solution
The optical device is a concave mirror because when light rays from a distant object (here it is Sun) fall on this mirror, its image is formed at the focus of the mirror on the same side as the object. Thus in the given case, distance between the mirror and the screen is the focal length of the concave mirror. Hence, the focal length of the given device (concave mirror) is 24 cm.
APPEARS IN
RELATED QUESTIONS
State the two convenient rays that are chosen to construct the image by a spherical mirror for a given object? Explain your answer with the help of suitable ray diagrams.
How is the focal length of a spherical mirror related to its radius of curvature?
For an incident ray directed towards centre of curvature of a spherical mirror the reflected ray:
A point light source is kept in front of a convex mirror at a distance of 40 cm. The focal length of the mirror is 40 cm. Find the position of image.
Define the following term:
convex mirror
Define the following term in relation to concave mirror.
Aperture
What is the focal length (f) of a mirror?
