Advertisements
Advertisements
प्रश्न
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
Advertisements
उत्तर
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
संबंधित प्रश्न
Define the following term in the context of spherical mirrors:- Principal focus
We can obtain an enlarged and erect image by a convex mirror.
Name the spherical mirror which can produce a real and diminished image of an object.
The diverging lens in part (a) is replaced by a converging lens also of focal length 100 mm. The object remains in the same position and an image is formed by the converging lens. Compare two properties of this image with those of the image formed by the diverging lens in part (a).
Name the two kinds of spherical mirrors and distinguish between them.
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.
Figure shows a concave mirror with its pole at P, focus F and centre of curvature C. Draw ray diagram to show the formation of image of an object OA.
An object is placed at 4 cm distance in front of a concave mirror of radius of curvature 24 cm. Find the position of image. Is the image magnified?
The boxes in figure (a, b, c) represent mirrors; insert a mirror which will reflect the incident ray as shown in the diagram.
Visit a nearby hospital. You can also visit the clinic of an ENT specialist, or a dentist. Request the doctor to show you the mirrors used for examining ear, nose, throat and teeth. Can you recognise the kind of mirror used in these instruments?
