Answer:
[tex]-3.50[/tex] meter
Explanation:
A nearsighted person uses concave lens.
Given -
Far point i.e distance of object [tex]= - 3.5[/tex] meter
Distance of image is not given . Hence we will assume that the image can be formed at any distance. We will take "di" [tex]=[/tex] infinity
As we know
[tex]\frac{1}{f} = \frac{1}{di} + \frac{1}{df} \\[/tex]
Substituting the given values in above equation, we get -
[tex]\frac{1}{f} = \frac{1}{infinity} + \frac{1}{-3.50}\\ \frac{1}{f} = 0 + \frac{1}{-3.50}\\ f = -3.50[/tex]
Hence, the focal length of the contact lens is equal to [tex]-3.50[/tex] meter
