an astronomical telescope

[logistic_guy]

An astronomical telescope has its two lenses spaced \(\displaystyle 76.0 \ \text{cm}\) apart. If the objective lens has a focal length of \(\displaystyle 74.5 \ \text{cm}\), what is the magnification of this telescope? Assume a relaxed eye.

 

[khansaheb]

An astronomical telescope has its two lenses spaced \(\displaystyle 76.0 \ \text{cm}\) apart. If the objective lens has a focal length of \(\displaystyle 74.5 \ \text{cm}\), what is the magnification of this telescope? Assume a relaxed eye.

show us your effort/s to solve this problem.

 

[logistic_guy]

The magnification is determined from this formula:

\(\displaystyle M = - \frac{f_o}{f_e}\)

But we don't have the focal length of the eyepiece, \(\displaystyle f_e\), so we have to find it from the formula of the total focal length.

\(\displaystyle L = f_o + f_e\)
\(\displaystyle 76 = 74.5 + f_e\)

Then

\(\displaystyle M = - \frac{f_o}{f_e} = -\frac{74.5}{76 - 74.5} \approx -50\text{x}\)

where the negative sign means that the image is inverted and \(\displaystyle \text{x}\) means times, in other words, the inverted image is \(\displaystyle 50\) times larger than the real image.

 

[Steven G]

First makes post with no work shown and then posts the solution. This is in violation of the posting guidelines.
Reported this OP to the admin---again