Prove that spherical mirror formula is applicable equally to a plane mirror.
Text Solution
Verified by Experts
The spherical mirror formula is `(1)/(u) + (1)/(v) = (1)/(f)` …(i) For a plane mirror, `R = oo` `f = (R )/(2) = oo` Form (i), `(1)/(u) + (1)/(v) = (1)/(oo) = 0` or `(1)/(v) = -(1)/(u)` or `v = -u` As `u` is negative, `v` becomes +. Hence, image is formed behind the mirror at the same distance as the object is in front of it. This is what happens in a plane mirror. Hence the desired result.
Topper's Solved these Questions
OPTICS
PRADEEP|Exercise Very short answer question|5 Videos
OPTICS
PRADEEP|Exercise very short answer questions|1 Videos
The formula governing reflection of light from a spherical mirror is (1)/(v) + (1)/(u) = (2)/(R ) , where u = distance of object from pole of mirror, upsilon = distance of image from pole of mirror f = focal length of mirror, R = radius of curvature of mirror. This is known as mirror formula and is applicable equally to concave mirror and convex mirror. m = (I)/(O) = (upsilon)/(u) Read the above passage and answer the following questions : (i) An object is held at a distance of 30 cm in front of a concave mirror of radius of curvature 40 cm . Calculate distance of the image from the object ? What is linear magnification of the mirror ? (ii) The object is moved to a distance of 40 cm in front of the mirror. How is focal length of mirror affected ? (iii) What values of life do you learn from the mirror formula ?
