A dentist obtains a linear magnification of 4 of a hole in a tooth by placing a concave mirror at a distance, of 2.0cm from the tooth. The radius of Curvature of the mirror is
-
A.
5.3cm -
B.
3.2cm -
C.
2.7cm -
D.
1.6cm
Correct Answer: Option B
Explanation
v = 4u, if u = 2cm, v = 8cm
F = (frac{uv}{u + v})
= (frac{2 times 8}{2 + 8})
= 1.6cm
r = 2F
= 2 x 1.6
= 3.2cm