A convex mirror forms an image one-fourth the size of the object. If the object is at a distance of 0.5 m from the mirror, the focal length of the mirror is

Question

A convex mirror forms an image one-fourth the size of the object. If the object is at a distance of 0.5 m from the mirror, the focal length of the mirror is (A) 0.17m (B) -1.5m (C) 0.4m (D) -0.4m

Tardigrade Admin · Accepted Answer

(f/f - u)=(1/4)=(f/f - (. - 0.5 .)) Or 4f=f+0.5 or 3f=0.5 Or f=(0.5/3)m=0.17m

Q. A convex mirror forms an image one-fourth the size of the object. If the object is at a distance of $0.5 m$ from the mirror, the focal length of the mirror is

$0.17 m$

$- 1.5 m$

$0.4 m$

$- 0.4 m$

$\frac{f}{f - u} = \frac{1}{4} = \frac{f}{f - ( - 0.5 )}$
Or $4 f = f + 0.5 or 3 f = 0.5$
Or $f = \frac{0.5}{3} m = 0.17 m$

Q. A convex mirror forms an image one-fourth the size of the object. If the object is at a distance of 0.5m from the mirror, the focal length of the mirror is

0.17m

−1.5m

0.4m

−0.4m