1.

A person cannot see clearly distance more than 40 cm . How much power of lens he should be advised to use?

Answer»

HERE IS THE SOLUTION;

◆According to the QUESTION;

u= -40 CM 【 Near Point 】

v = -∞

F=?

◆ Formula Used

\frac{1}{f} = \frac{1}{v} - \frac{1}{u} \\ \\ \frac{1}{f} = \frac{1}{ - \infty } - \frac{1}{40} \\ \\ \frac{1}{f} = - \frac{1}{40} \\ \\ = > f = - 40 \: cm

◆ Using Lens Formula;

P= ?

f= -40 Cm

p = \frac{1}{f} \\ \\ p = \frac{1}{ - 40} \\ \\ p = \frac{100}{ - 40 } \\ \\ p = - 2.5 \: d

So, the power is -2.5 D.

HOPE IT HELPS


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