What is the accuracy with which corrective lenses can be produced?

Assume that the near point of a hyperopic (farsighted) eye is 0.936 m in front of the eye. A lens is used to let the eye see clearly an object that is 0.250 m in front of the eye. Ignore the small distance from the lens to the eye. What is the power of the lens (in diopters; answer sign and magnitude)?

A book held 9.00 cm from a magnifiying lens of focal length f = 12.5 cm. Find the magnification for the book. Submit Answer Tries 0/99 Do the same for when the book is held 10.00 cm from the magnifier. Submit Answer Tries 0/99 Do the same for when the book is held 11.00 cm from the magnifier. (Comment on the trend in m as the object distance increases as in these three calculations.) Submit Answer Tries 0/99

An individual is nearsighted; his near point is 11.0 cm and his far point is 51.0 cm. (a) What lens power is needed to correct his nearsightedness? 1.96 X The response you submitted has the wrong sign. diopters (b) When the lenses are in use, what is this person's near point? 11 X Your response differs from the correct answer by more than 10%. Double check your calculations. cm