Question

the focal length of a lens is +0.50m the power of the lens and type are​

Answer 1

Answer:

A concave lens of focal length 2m

Power of combination P=1.5 dioptre

Power of convex lens having focal length of 0.5m,  P1=0.51 dioptre

Using P=P1+P2

∴ 1.5=0.51+P2

We get P2=−0.5 dioptre

Thus focal length of second lens f2=P21 

⟹ f2=−0.51=−2m (negative sign implies the lens must be a concave lens)

Thus second lens could be concave lens of focal length 2m.