Question
Fri November 04, 2011 By: Raghu Rao

# A REAL OBJECT IS LOCATED IS LOCATED AT ZERO END OF A METER STICK. A CONCAVE MIRROR LOCATED AT 100 cm END OF THE METER STICK FORMS AN IMAGE OF THE OBJECT AT THE 70cm POSITION. A CONVEX MIRROR PLACED AT THE 60cm POSITION FORMS A FINAL IMAGE AT THE 10 cm POINT WHAT IS THE RADIUS OF CURVATURE OF THE CONVEX MIRROR?

Expert Reply
Wed November 09, 2011
here for concave mirror
u = 100 cm.
v= 70 cm.
we know
1/f = 1/v +1/u.
1/f =1/100 +1/70
on solving
f =7000/170 =41.17 cm.
radius of curvature for concave mirror = 2 * 41.7 cm = 82.35 cm

for convex mirror image formed by concave mirror act as object for comvex mirror so for convex mirror
u = -10 cm.
v= 50 cm.
again
1/f = 1/v +1/u
1/f = 1/50 -1/10.
1/f =(1-5)/50.
1/f = -4/50
1/f = -4/50
f= -50/4.
f= -12.5 cm
radius of curvature for convex mirror = 2 * focal length of convex mirror.
radius of curvature for convex mirror = 2 *12.5 =25 cm.
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