Question

An object is placed at a distance of 10 cm from a concave mirror of focal length 20 cm find magnification

Answer 1

$\Large\underline{\underline{\sf Given:}}$

• Object is placed at distance (u) = -10cm

• Focal lenght (f) = -20cm

$\Large\underline{\underline{\sf To\:Find:}}$

• Magnification of mirror.

$\Large\underline{\underline{\sf Formula\:Used:}}$

✮$\large{\boxed{\sf \pink{\dfrac{1}{f}=\dfrac{1}{v}+\dfrac{1}{u}}}}$

✮$\large{\boxed{\sf \pink{m=\dfrac{-v}{u}}}}$

$\Large\underline{\underline{\mathfrak \orange{Solution}:}}$

$\large\implies{\sf \dfrac{1}{f}=\dfrac{1}{v}+\dfrac{1}{u} }$

$\implies{\sf \dfrac{1}{-20}=\dfrac{1}{v}+\right(-\dfrac{1}{10}\left)}$

$\implies{\sf \dfrac{1}{-20}=\dfrac{1}{v}-\dfrac{1}{10} }$

$\implies{\sf \red{v=+20\:cm }}$

✮ Magnification (m) :

$\large\implies{\sf m=\dfrac{-v}{u}}$

$\implies{\sf m=\dfrac{-20}{10}}$

$\implies{\sf \red{m=-2 }}$

$\Large\underline{\underline{\mathfrak \orange{Answer:}}}$

☆Magnification of mirror is -2