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The image of a needle placed 45cm from a lens is formed on a screen placed 90cm on the other side of lens.Find displacement of image if object is moved 5cm away from lens

The image of a needle placed 45cm from a lens is formed on a screen placed 90cm on the other side of lens.Find displacement of image if object is moved 5cm away from lens

Grade:12

1 Answers

SAHIL
3778 Points
7 years ago

first of all we will  calculate focal lenght from lens formula 1/v - 1/u = 1/f

 put u = -45

1/90 + 1/45 = 1/f 

it gives f = 30

Now again use lens formula and obtain image distance for u = - 50

you will get v = 75

Displacement = 90 - 75 = 15 cm

 

thanks

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