Question

. An object of height 10 cm is placed at a distance of 40 cm, infront of a concave mirror of focal length 20.0 cm. Find
the length of image.​

Answer 1

Answer:

13cm

Explanation:

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how are you?

Answer 2

$\maltese \: \red{\mid{\underline{\overline{\textbf{Answer}}}\mid}}$

It is given that :-

• Height of object = 10cm
• Object distance = 40cm
• Image distance = v = ?
• Focal length of mirror = 20cm
• Height of image =?

Now according to mirror formula :

$\maltese \: \frac{1}{f} = \frac{1}{v} + \frac{1}{u}$

$\maltese \: f = \frac{uv}{u + v}$

Now, after inputting the known values in this equation we get :

$\maltese \: 20 = \frac{ - 40v}{40 - v}$

$\maltese \: 800 - 20v = - 40v$

$\maltese \: 800 = - 40v + 20v$

$\maltese \: 800 = - 20v \\ \\ \maltese \: v = \frac{ - 800}{20}$

$\maltese \: \cancel \frac{ - 800}{20} = 40cm$

Therefore the image distance is 40cm.

Now we know that ratio of height of image to height of object is equals to ratio of image distance to object distance.

$\frac{h_i}{h_o} = \frac{v}{u}$

After inputting the values we get :

$\frac{h_i}{10} = \frac{40}{40}$

$\frac{h_i}{10} = \cancel \frac{40}{4 0} = \frac{1}{1}$

$h_i = 10cm$

Therefore the length of image formed is 10cm

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BY SCIVIBHANSHU

THANK YOU

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