Hey there! I'm new and I have an exercise to solve I don't understand:

"in the lab exercises for the Optical instruments the following relationship is used:

i/p = s/f

With s=i-f. In the Case of a microscope, the quantitiy s can be identified with the tube length of the microscope, because both the fokal length of the objective 'f ob' As well As the fokal length of the eye piece 'f ey' is small compared to s.

Proof that the relationship is correct."

I just don't understand and don't Know what to Look up. Help Gould Be great!

Thanks, pillow :)