Question

The sun is 150,000,000 km from earth; its diameter is 1,400,000 km. A student uses a 5.2-cm-diameter lens with f = 10 cm to cast an image of the sun on a piece of paper. Where should the paper be placed relative to the lens to get a sharp image?

Answer 1

Answer:

The paper is placed on the focus of the lens then we get the sharp image.

Explanation:

Given that,

Object distance = 150000000 km

Diameter = 1400000 km

Diameter of lens = 5.2 cm

Focal length = 10 cm

We need to calculate the image distance

Using formula of lens

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

$\dfrac{1}{v}=\dfrac{1}{10}+\dfrac{1}{15\times10^{7}}$

$\dfrac{1}{v}=\dfrac{1}{1.0\times10^{-4}}+\dfrac{1}{15\times10^{7}}$

Here,

$v=0.0001\ km$

$v=1.0\times 10^{-4}\ km$

Hence, The paper is placed on the focus of the lens then we get the sharp image.