Question

the image of an object formed by a lens is of m -1. if the distance between the object and the image is 60 cm , what is the focal length of the lens?
now please

Answer 1

Given :

m = -1
u = -60 cm
f = ?
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m = v/u
-1 = v/-60
v = +60 cm
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Using lens formula ;

(1/f) = (1/v)-(1/u)

1/f = (1/60) - (1/-60)

1/f =(1/60) + (1/60)

f = 60/2

f = +30 cm
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Hence the focal length of the convex lens is 30 cm