Question

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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Answer 1

Explanation:

u = -60 cm, v = +120

sol ur answer

Object distance u=−60 cmImage distance v=+120 cmUsing lens formula,1/f=1/v−1/u1/f=1/120−(−1/60)=+40cmH(image) / H(object) = v/uHi=−120/60X5=

Answer 2

Answer:

ᴜꜱɪɴɢ ,

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

ᴡᴇ ɢᴇᴛ ,

$\frac{1}{f} = \frac{1}{120} - \frac{1}{ - 60} = \frac{1 + 2}{120}$

$☞f = 40 \: cm \:$

$m = \frac{v}{u} = \frac{h_{1}}{ h_{0} }$

ᴛʜᴇʀᴇꜰᴏʀᴇ ,

$h_{1} = h_{0} \times \frac{v}{u}$

$= 5 \times \frac{120}{60} = 10 \: cm \: .$