Posted by **ceasar3** on Tuesday, December 6, 2011 at 5:25am.

An astronomical telescope has an object lens of 80cm and an eyepiece of 5cm focal length.If the image is formed 25cm from the eye piece when a distant object is viewed by the eye close to the eye piece ,detemine the magnifying power of the telescope.What is the best position of the eye?

- physics -
**drwls**, Tuesday, December 6, 2011 at 7:42am
I have some issues with that question, and am not going to answer it they way they want.

It is much comfortable to have the objective image at the focal point of the eyepiece, so that the eye sees an image at infinity. In that case, the magnification of the telescope is obtained from the formula

M = f(obj)/f(eyepiece)

which equals 16, in this case. That is not much of a telescope. A true astronomical telescope will have a longer objective focus longer than 80 cm and an eyepiece with a shorter focal length than 5 cm, unless you are just using binoculars.

- maths -
**chrystabelle1**, Tuesday, December 6, 2011 at 8:34am
If y=e(power x)+ e(power-x)/2. find x when y=1

- Note to chrystabelle -
**drwls**, Tuesday, December 6, 2011 at 10:29am
Post that as a separate question, with subject math

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