A statue that is 10.4 cm tall is placed 4.8 cm in front of a concave lens.The image is 4.0 cm from the lens.How tall is the image?
A)13 cm
B)8.7 cm
C)5.4 cm
D)1.8 cm

Question

Quizplus · Accepted Answer

We can use the thin lens equation:
1/f = 1/di + 1/do
where f is the focal length of the concave lens, di is the distance of the image from the lens, and do is the distance of the object from the lens.
Since it is a concave lens, f is negative.
We can rearrange the equation to solve for the image distance:
1/di = 1/f - 1/do
1/di = -1/4.8 - 1/-10.4
di = -6.53 cm (the negative sign indicates that the image is virtual)
To find the height of the image, we can use the magnification equation:
magnification = hi/ho = -di/do
where hi is the height of the image and ho is the height of the object.
Rearranging the equation, we get:
hi = magnification x ho x do
Plugging in the values, we get:
hi = (-di/do) x ho x do
hi = -(-6.53/10.4) x 10.4
hi = 6.53 cm
Therefore, the height of the image is 6.53 cm. The answer is B) 8.7 cm, which is not one of the choices.

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