The sun is 150,000,000 km from earth; its diameter is 1,400,000 km. A student uses a 4.6-cm-diameter lens with f = 10 cm to cast an image of the sun on a piece of paper. What is the diameter of the image on the paper?

Explanation:

the image distance can be calculated using below formula of lens

1/v=1/- 1/u

Where

u= Object distance = 15×10^7km

Diameter = 1400000 km

Diameter of lens = 4.6 cm

f= Focal length ( 10 cm)= 1×10^-4

We can substitute to the above formula we have

1/15×10^7km+1/1×10^-4

V=0.001km

Therefore, paper stayed on the focus, hence the sharp image

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