Calculate the correct answer:
A person needs a lens of power \(-5\ dioptre\) for correcting his distant vision. For correcting his near vision he needs a lens of power \(+3.5\ dioptre\). What is the focal length of the lens required for correcting?
i. distant vision
ii. near vision
i. distant vision
ii. near vision
The power (\(P\)) of a lens of focal length (\(f\)) is given by the relation,
Case i:
Power of the lens used for by the person correcting distant vision \(=\ −5\ D\)
Distant vision of the person \(=\) \(m\)
Case ii:
Power of the lens used by the person for correcting near vision \(=\ +3.5\ D\)
Near vision of the person \(=\) \(m\)
[Note: Enter your answer with two decimal digits]