the image formed on a screen by a concave mirror of radius 20 cm is 3 times the size of the object. what is the distance of the screen from

Question

the image formed on a screen by a concave mirror of radius 20 cm is 3 times the size of the object. what is the distance of the screen from the mirror?​

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Khải Quang 5 months 2021-08-19T09:06:22+00:00 1 Answers 0 views 0

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    2021-08-19T09:07:33+00:00

    Given that,

    Radius of mirror = 20 cm

    Size of image = 3 times of size of object

    We need to calculate the distance of the screen from the mirror

    Using formula of magnification

    m=-\dfrac{h'}{h}=\dfrac{v}{u}

    -\dfrac{h'}{h}=\dfrac{v}{u}

    Where, h’ = size of image

    h = size of object  

    v = image distance from mirror

    u = object distance from mirror

    Put the value into the formula

    -\dfrac{3h}{h}=\dfrac{-v}{u}

    \dfrac{3}{1}=\dfrac{v}{u}

    v=3u

    The distance of image will three times of object distance.

    Hence, The distance of the screen from the mirror is 3u.

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