A person looks at a gem using a converging lens with
a focal length of 12.5 cm. The lens forms a virtual
image 20.0 cm from the lens. Determine the magni-
fication. Is the image upright or inverted?



Answer :

xzwoah

Answer:

To determine the magnification produced by the lens, we can use the magnification formula:

\[ M = \frac{-d_i}{d_o} \]

Where:

- \( M \) = Magnification

- \( d_i \) = Image distance (distance of the image from the lens)

- \( d_o \) = Object distance (distance of the object from the lens)

Given:

- \( f = 12.5 \) cm (focal length)

- \( d_i = 20.0 \) cm (image distance)

- Since the image is virtual, it is formed on the same side as the object, so \( d_o \) is negative.

First, let's find the object distance \( d_o \) using the lens formula:

\[ \frac{1}{f} = \frac{1}{d_o} + \frac{1}{d_i} \]

\[ \frac{1}{12.5} = \frac{1}{d_o} + \frac{1}{20.0} \]

\[ \frac{1}{d_o} = \frac{1}{12.5} - \frac{1}{20.0} \]

\[ \frac{1}{d_o} = \frac{8}{100} - \frac{5}{100} \]

\[ \frac{1}{d_o} = \frac{3}{100} \]

\[ d_o = \frac{100}{3} \]

\[ d_o = -33.3 \, \text{cm} \]

Now, let's calculate the magnification \( M \):

\[ M = \frac{-d_i}{d_o} \]

\[ M = \frac{-20.0}{-33.3} \]

\[ M ≈ \frac{2}{3} \]

Now, to determine whether the image is upright or inverted, we need to check the sign of the magnification. Since the magnification \( M \) is positive, the image is upright.