Question

one student uses lens of focal length +50 cm and another of -50cm state the nature and find the power of each lens?

Answer 1

focal length +50 of a lens tells that it is convex lens as its focal length is in plus......its power ,p=1/f(focal length)
p=1/+50
=+0.02 dioptres......

the minus sign of another focal length tells that it is concave lens.....its power,p=1/f
p=1/-50
=-0.02 dioptres.

Answer 2

• If the power of the lens is +ve,then it is a convex lens.
• If the power of lens is -ve the it is a concave lens.
• As the value of "f" is given in cm we should convert it to meter.
• In case of "f" =50cm: P= 1/f(in m)

                                        P=100/f(in cm)

                                      P=100/50,      P=2D.(convex lens)

• In Case of "f"=-50. : p=100/-50

                                      P=  -2D.(concave lens)

• The Other Answer is wrong as he didnt convert the unit of "f"from cm to m.
• Mark me as BRAINLIEST