Question

2. A 50 cm tall object is at a very large distance from a diverging lens. A virtual, erect and diminished image of
the object is formed at a distance of 20 cm in front of the lens. How much is the focal length of the lens ?
of lens B?​

Answer 1

Explanation:

..... Answer is in step by step......................

Answer 2

Explanation:

━☞Given:

• A 50 cm tall object is at a very large distance from a diverging lens.
• A virtual, erect and diminished image of
• the object is formed at a distance of 20 cm

━☞To Find:

the focal length of the lens B?

━☞Solution:

As an object is at a very large distance from a diverging lens

means v is very large so

$\frac{1}{v} = 0$

And using

$\frac{1}{v} - \frac{1}{u} = \frac{1}{f}$

we get f=-u

So we can say that

When an object is placed at a very large distance from a diverging lens, then the image is formed at the focus of the lens.

━☞Therefore, the focal length of the lens is 20 cm