Question

The magnification of convex mirror is 0.7cm when object is keep at the distance 30cm find the focal length​

Answer 1

Answer:

Given:-

• m=-0.7(magnification) of a covex mirror
• u=-30(Distance object)
• Focal length=??

$m = 0.7$

We know that;

$m = \frac{ - v}{u}$

$- 0.7 = \frac{ - v}{ - 30}$

$v = - 21$

We know that from mirror formula,

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

$\frac{1}{ - 21} + \frac{1}{30} = \frac{1}{f}$

$\frac{ - 30 + 21}{630} = \frac{1}{f}$

$\frac{ - 1}{70} = \frac{1}{f}$

So focal lenght =(-70)

Hope it helps

$\frac{ - 9}{630} = \frac{1}{f}$