A short sighted person is wearing specs of power `-3.5 D`. His doctor prescribes a correction of `+ 2.5 D` for his near vision. What is focal length of his distance viewing part and near vision. What is focal length of his distance viewing part and near vision part ?

A short sighted person is wearing specs of power `-3.5 D`. His doctor

1.	A short sighted person is wearing specs of power `-3.5 D`. His doctor prescribes a correction of `+ 2.5 D` for his near vision. What is focal length of his distance viewing part and near vision. What is focal length of his distance viewing part and near vision part ?
Answer» Correct Answer - `-28.5 cm ; 16.7 cm` For distance viewing part, `P_1 = -3.5 D` `:. f_1 = (100)/(P_1)=(100)/(-3.5) cm = -28.5 cm` For near vision part, `P_1 + P_2 = P` `P_2 = P - P_1 = 2.5 D - (-3.5 D) = 6.0 D` `f_2 = (100)/(P_2) = (100)/(6.0) = 16.7 cm`.

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A short sighted person is wearing specs of power `-3.5 D`. His doctor prescribes a correction of `+ 2.5 D` for his near vision. What is focal length of his distance viewing part and near vision. What is focal length of his distance viewing part and near vision part ?

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