What is the focal length of a convex lens of focal length 30cm in contact with a concave lens of focal length 20 cm? is the system a converging or a diverging lens ? Ignore thickness of the lenses.

What is the focal length of a convex lens of focal length 30cm in cont

1.	What is the focal length of a convex lens of focal length 30cm in contact with a concave lens of focal length 20 cm? is the system a converging or a diverging lens ? Ignore thickness of the lenses.
Answer» Solution :`f_(1) = 30 CM , f_(2) = - 20 cm ` F= `(f_(1)f_(2))/(f_(1) + f_(2))= (30 XX -20)/(30- 20) = (-600)/(10) = - 60 ` cm .f. being negative, the combination is a DIVERGING lens.

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What is the focal length of a convex lens of focal length 30cm in contact with a concave lens of focal length 20 cm? is the system a converging or a diverging lens ? Ignore thickness of the lenses.

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