Question

Frank is nearsighted and his glasses require a prescription of -1.2 D. One day he can't find his glasses, but he does find an older pair with a prescription of -1.0 D. Part A What is the most distant object that Frank can focus on while wearing this older pair of glasses? Express your answer with the appropriate units. ? s = 1 m

step by step please

Answer 1

let d is his near point.

when he used -1.2 D lens.
focal length, f = 1/(-1.2)

= -0.833 m

= -83.3 cm

object distance, u = infinite
image distance, v = d

now use, 1/u + 1/v = 1/f

1/infinite + 1/d = 1/f

==> d = f

= -83.3 cm

so, |d| = 83.3 cm

when he used lens with prescription -1.0 D

f = 1/P

= 1/(-1)

= -1 m

= -100 cm

let u is the most distanct object that Frank can focus
v = -0.833 m

now use,

1/u + 1/v = 1/f

1/u = 1/f - 1/v

1/u = 1/(-100) - 1/(-83.3)

u = 499 cm (or) 4.99 m <<<<<<<<<<<----------------Answer