Question

two thin lenses of power + 3.5Dand 2.50 are placed in contact. find tha power and focal length of the lens combination

Answer 1

To find the power of a combination of lenses, we have to add the different lenses to get the result.

Hence, in this case, P1 = +3.50 and P2 = +2.50.

Therefore, the resultant power, P = P1 + P2 = +3.50 + 2.50 = +6.00.

For finding the focal length of the lens combination, we have by the formula, f (in meter) = 1/P (in D).

Hence, substituting the values in the formula, we get, f = 1/6 = 0.16 meter = 16 cm.