Questions
6Define the principal focus of a concave mirror.
The principal focus of a concave mirror is the point on the principal axis where all reflected rays parallel to the principal axis converge after reflection.
Name a mirror that can give an erect and enlarged image of an object.
A concave mirror gives an erect and enlarged image when the object is placed between the pole and the principal focus.
Why do we prefer a convex mirror as a rear-view mirror in vehicles?
Convex mirrors give an erect, diminished image and a wider field of view, allowing drivers to see more area behind the vehicle.
Find the focal length of a convex mirror whose radius of curvature is 32 cm.
For a spherical mirror, f = R/2. So the focal length of a convex mirror with radius of curvature 32 cm is 32/2 = 16 cm.
State the laws of refraction of light.
The incident ray, refracted ray, and normal all lie in the same plane. The ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant for a given pair of media (Snell's law).
A concave mirror produces three times magnified (enlarged) real image of an object placed at 10 cm in front of it. Where is the image located?
Using the magnification formula m = -v/u, with m = -3 (real image), u = -10 cm, we get -3 = -v/(-10), so v = -30 cm. The image is located 30 cm in front of the mirror.