Use the thin-lens equation to show that the magnification for a thin lens is determined by its focal length and the object distance and is given by \(m=f /\left(f-d_{\mathrm{o}}\right)\)

Short Answer

Expert verified
To show that the magnification for a thin lens is determined by its focal length and the object distance and is given by \(m = \frac{f}{f - d_o}\), we used the Thin-Lens Equation: \(\frac{1}{f} = \frac{1}{d_o} + \frac{1}{d_i}\). Rearranging it to isolate the image distance, we found that \(d_i = \frac{f d_o}{f - d_o}\). Then, by expressing magnification as \(m =\frac{d_i}{d_o}\) and substituting the expression for \(d_i\) in terms of \(f\) and \(d_o\), we derived the final magnification equation: \(m = \frac{f}{f - d_o}\).

Step by step solution

01

Apply the Thin-Lens Equation

Recall the Thin-Lens Equation: \[ \frac{1}{f} = \frac{1}{d_o} + \frac{1}{d_i} \] where: - \(f\) is the focal length of the lens - \(d_o\) is the object distance (the distance between the object and the lens) - \(d_i\) is the image distance (the distance between the lens and the image) Now, we need to express the image distance \(d_i\) in terms of the focal length \(f\) and object distance \(d_o\).
02

Solve for the image distance

Rearrange the Thin-Lens Equation to isolate the image distance \(d_i\): \[ d_i = \frac{f d_o}{f - d_o} \]
03

Express the magnification in terms of object and image distances

Recall that the magnification \(m\) is the ratio of the image distance to the object distance: \[ m = \frac{d_i}{d_o} \] Substitute the expression for \(d_i\) from Step 2 into the magnification equation: \[ m = \frac{\frac{f d_o}{f - d_o}}{d_o} \]
04

Simplify the magnification equation

By dividing through the fractions, we can simplify the magnification equation: \[ m = \frac{f d_o}{(f - d_o) d_o} \] \[ m = \frac{f}{f - d_o} \] Now we've derived a magnification equation for a thin lens in terms of its focal length and the object distance. As required, the formula is: \[ m = \frac{f}{f - d_o} \]

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