39.) Marooned on a desert island and with a lot of time on your hands, you decid

Question

39.) Marooned on a desert island and with a lot of time on your hands, you decide to disassemble your glasses to make a crude telescope with which you can scan the horizon for rescuers. Luckily you're farsighted, and, like most people, your two eyes have different lens prescriptions. Your left eye uses a lens of power +4.5D, and your right eye's lens is +3.0 D.

a.) Which lens should you use for the objective and which for the eyepiece? Explain.

b.)What will be the magnification of your telescope?

c.) How far apart should the two lenses be when you focus on distant objects?

Please show all work.

Explanation / Answer

(a) The lens with the smaller refractive power has the longer focal length and should be used as the object— that’s the lens with P = +3.0 D. The +4.5 D lens should be used as the eyepiece. --------------------------------------------------------------------------------------------------- (b) the magnification of telescope M =-f_obj/f_eye =-p_eye/p_obj =-4.5 D/3.0 D =-1.5 ------------------------------------------------------------------------------------------------- (c) In a telescope the lenses should be a distance apart equal to the sum of their focal lengths d =f_eye+f_obj =(1/p_obj)+(1/p_eye) =(1/3.0 D)+(1/4.5 D) =0.56

Related Questions

Navigate

• Browse (All)
• Browse 3
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.