A refracting telescope is used to view the Moon. The focal lengths of the objective and eyepiece are \(+2.40 \mathrm{m}\) and \(+16.0 \mathrm{cm},\) respectively. (a) What should be the distance between the lenses? (b) What is the diameter of the image produced by the objective? (c) What is the angular magnification?

Short Answer

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Answer: (a) The distance between the lenses (l) is calculated using the lens formula and the given values of the focal lengths of the objective and eyepiece lenses. (b) The diameter of the image produced by the objective (D_image) is found using the relationship between the distances and the diameters of the image and the moon. (c) The angular magnification (M) is determined by the ratio of the focal lengths of the objective and eyepiece lenses.

Step by step solution

01

Find the distance between the lenses (l)

To find the distance between the lenses (l), we will use the lens formula: $$ \frac{1}{f} = \frac{1}{D_o} + \frac{1}{D_i} $$ where f is the focal length of the objective lens, \(D_o\) is the distance from the objective to the image, \(D_i\) is the distance from the eyepiece to the image. We are given \(f_o = 2.4m\) and \(f_e = 0.16m\). We can define \(l = D_o + D_i\) and we know that the image is formed at the focal length of the eyepiece so \(D_i = f_e\). So the equation becomes: $$ \frac{1}{2.4} = \frac{1}{D_o} + \frac{1}{0.16} $$
02

Calculate the distance from the objective lens to the image (\(D_o\))

To find \(D_o\), we will solve the equation we obtained in step 1: $$ \frac{1}{D_o} = \frac{1}{2.4} - \frac{1}{0.16} $$ $$ D_o = \frac{1}{\frac{1}{2.4} - \frac{1}{0.16}} $$ Calculate the value of \(D_o\).
03

Find the distance between the lenses (l)

Now that we have \(D_o\), we can find the distance between the lenses (l) using the relationship \(l = D_o + D_i\): $$ l = D_o + f_e $$ Calculate the value of l.
04

Find the diameter of the image produced by the objective

To find the diameter of the image produced by the objective, we can use the relationship: $$ \frac{D_o}{f_o} = \frac{D_{image}}{D_{moon}} $$ where \(D_{image}\) is the diameter of the image produced by the objective and \(D_{moon}\) is the diameter of the moon. We know that the diameter of the moon is \(3.474 \times 10^6\mathrm{m}\). Now we can solve for \(D_{image}\): $$ D_{image} = \frac{D_o \times D_{moon}}{f_o} $$ Calculate the value of \(D_{image}\).
05

Find the angular magnification

The angular magnification (M) of the telescope is given by the ratio of the focal lengths of the objective and eyepiece lenses: $$ M = \frac{f_o}{f_e} $$ Calculate the value of M.

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