Question

calculate the focal length of a convex lens which produces a virtual image at a distance of 50 cm of an object placed 20 CM in front of it

Answer 1

negative of hundred upon three

Answer 2

Answer:

Focal length of the given convex mirror will be 33.34cm, here's how;

Explanation:

Given: v = -50cm

          u = -20cm

To Find: f = ?

Solution:

using the lens formula, ie.

$\frac{1}{f}$ = $\frac{1}{v}$ - $\frac{1}{u}$

$\frac{1}{f}$ = -$\frac{1}{50\\}$ - (-$\frac{1}{20}$)

$\frac{1}{f}$= -$\frac{1}{50\\}$+ $\frac{1}{20}$

$\frac{1}{f}$ = (-$\frac{2+5}{100}$)                                                              {LCM of 50 and 20 is 100}

$\frac{1}{f}$= $\frac{3}{100}$

$\frac{1}{f}$ = $\frac{1}{33.34\\}$

f = 33.34

Therefore we can say that the focal length of this convex lens is +33.34