Question

An object is place 30.5 cm from a convex lens that has a focal length of 8.0cm.where is the image ?

Answer 1

Answer:

Image is between F and 2F. And the exact location is:

q = 10.84 cm

Explanation:

The convex lens form different kinds of images with different sizes and locations, for the different positions of an object. In this case, the object is placed 30.5 cm from the convex lens with a focal length of 8 cm. This means that it is the case of the object placed beyond 2F. In this case, the image formed has the following characteristics:

1. Image is real.

2. Image is inverted

3. Image is diminished

4. Image is located between F and 2F

For exact location we use the thin lens formula:

$\frac{1}{f} = \frac{1}{p} + \frac{1}{q}$

where,

f = focal length = 8 cm

p = object distance = 30.5 cm

q = image distance = ?

Therefore,

$\frac{1}{8\ cm} = \frac{1}{30.5\ cm} + \frac{1}{q} \\\frac{1}{8\ cm} - \frac{1}{30.5\ cm} = \frac{1}{q}$

q = 10.84 cm