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Light Reflection and Refraction
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02/12/2020 1:06 pm
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The image of an object placed at 60 cm in front of a lens is obtained on a screen at a distance of 120 cm from it. Find the focal length of the lens. What would be the height of the image if the object is 5 cm high?
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02/12/2020 1:10 pm
u = -60 cm, v = +120 cm
Using, 1/f = 1/v - 1/u, we get
1/f = 1/120 - 1/-60 = 1 + 2/120
⇒ f = 40 cm
m = v/u = h1/ho
∴ h1 = ho x v/u
= 5 x 120/60 = 10 cm