A nearsighted person cannot see objects clearly beyond 20.7 cm (her far point).

Question

A nearsighted person cannot see objects clearly beyond 20.7 cm (her far point).

(a) If she has no astigmatism and contact lenses are prescribed for her, what power lens is required to correct her vision?
diopters

(b) What type of lens is required to correct her vision?

convergingdiverging   

The refracting telescope at the Yerkes Observatory has a 1.00-m diameter objective lens of focal length 20.0 m. Assume it is used with an eyepiece of focal length 3.30 cm.

(a) Determine the magnification of Mars as seen through this telescope.


(b) Are the Martian polar caps right side up or upside down?

right side upupside down   

Explanation / Answer

1)

The far point of the persion is 20.7 cm

   So the focal length of lense required is, f = -20.7 cm

   a) Power of lense, P = 1/f = -1/20.7 = -0.0483 diopters

   b) So she requries a diverging lense of power -0.0483 diopters

2)

a) m = -f0/fe =20/ 0.0330 = -606

b)since m<0 image is inverted (upside down)

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