What power contact lens must be used to correct the vision of a ...

[ts19998]

What power contact lens must be used to correct the vision of a nearsighted person whose far point is 40 cm?
 
  A) 2.5 diopters
  B) -2.5 diopters
  C) -3.6 diopters
  D) -4.0 diopters
  E) 4.0 diopters

Question 2

The focal length of a thin lens is 40 mm and its aperture diameter is 10 mm. What is the f-number of this lens?
 
  A) f/4.0
  B) f/2.0
  C) f/5.6
  D) f/0.30
  E) f/0.40

[laurnthompson]

Answer to Question 1

Thank you soo much

Answer to Question 2

A

[ts19998]

Thanks for the timely response, appreciate it

[bigcheese9]

Gracias!