Question

the focal length of a convex lens is 50cm if an object is kept at is distance of 75cm the lens then find the image distance and magnification produced by the lens
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Answer 1

Answer:

f = 50cm

u = -75 cm

$\frac{1}{v} = \frac{1}{u } + \frac{1}{f} \\ \: \: \: \: \: = - \frac{1}{75} + \frac{1}{50} \\ \: \: \: \: \: = \frac{ - 2 + 3}{150} = \frac{1}{150 } \\ v = 150cm \\ m = \frac{v}{u } = \frac{150}{ - 75} = - 2$

Answer 2

Answer:

lens formula:

1/f=1/v-1/u

Explanation:

1/v=1/f+1/u

here,f=50,u=-75

so,

1/v=1/50-1/75

1/v=3-4/150

1/v=-1/150

v=-150

now,

m=-h/h=-v/u

m=-(-150)/50

m=150/50

m=30

Hence proved