Question

If an object is kept 20 cm away from lens and image is formed 40 cm away from the lens,then whatis the focal length ofthelens and what type of lens it is? Find the magnification also ?​

Answer 1

Your answer is in the image attached..........

One thing your question is insufficient....as you have not given the data about the position of the image.......

After putting the correct data you will get your answer by the same process......which I have followed.........

plzzz mark me as brainliest.....

Answer 2

Answer: Focal length=40/3cm, Type of lens=convex, Magnification=-2

Explanation:

We need to find:

1. Focal length of the lens
2. Type of lens
3. Magnification

Given:

$u=-20cm\\v=+40cm\\\\By\ the\ lens\ formula:1/v-1/u=1/f\\(1/40)-(-1/20)=1/f\\f=-40/3cm=13.3cm\\m=v/u=40/-20=-2$

Negative sign of magnification shows that a real image is formed. It also indicates that the lens is converging i.e convex lens.