Advertisements
Advertisements
Question
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.
Advertisements
Solution
Given,
u = 40 cm (negative)
f = 40 cm (positive)
Mirror formula:
`1/u + 1/v = 1/f`
Substituting the values in the formula above, we get,
`- 1/40 + 1/v = 1/40`
`1/v = 1/40 + 1/40`
`1/v = (1 + 1)/40`
`1/v = 2/40`
`1/v = 1/20`
⇒ v = 20 cm.
The image is behind the mirror at a distance 20 cm.
APPEARS IN
RELATED QUESTIONS
A student focused the Sun rays using an optical device 'X' on a screen S as shown.
From this it may be concluded that the device 'X' is a (select the correct option)
(A) Convex lens of focal length 10 cm.
(B) Convex lens of radius of curvature 20 cm.
(C) Convex lens of focal length 20 cm.
(D) Concave mirror of focal length 20 cm.
Write the formula for a lens connecting image distance (v), object distance (u) and the focal length (f). How does the lens formula differ from the mirror formula?
A student obtained on a screen the sharp image of a candle flame placed at the farther end of laboratory table using a concave mirror. For getting better value of focal length of the mirror, the teacher suggested to him to focus the sun. What should the student do?
(A) Should move the mirror away from the screen.
(B) Should move the mirror towards the screen.
(C) Should move the mirror and screen both towards the sun.
(D) Should move only the screen towards the sun.
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.
How will you distinguish between a plane mirror, a concave mirror and a convex mirror, without touching them?
Numerical problem.
The radius of curvature of a spherical mirror is 25 cm. Find its focal length.
Size of image of an object by a mirror having a focal length of 20 cm is observed to be reduced to 1/3rd of its size. At what distance the object has been placed from the mirror? What is the nature of the image and the mirror?
