A convex lens of focal length 40 cm is in contact with a concave lens of focal length 20 cm. The power of the combination is ________.

A convex lens of focal length 40 cm is in contact with a concave lens

1.	A convex lens of focal length 40 cm is in contact with a concave lens of focal length 20 cm. The power of the combination is ________.
Answer» Solution :HINT : Here `f_(1)=+40 CM = 0.4 m and f_(2)=-20cm =-0.2 m` `therefore""P_(1)=(1)/(f_(1))=+2.5 D and P_(2)=(1)/(f_(2))=-5.0D` `RARR""P=P_(1)+P_(2)=-2.5D`

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A convex lens of focal length 40 cm is in contact with a concave lens of focal length 20 cm. The power of the combination is ________.

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