Question

Find the height of the object place at a distance of 3 cm from the mirror forms an image at 12 cm with a height of 4 cm​

Answer 1

Answer:-

• Object Distance=u=3
• Image distance=v=12cm
• Image height=h'=4cm
• Object height=h=?

We know that

$\boxed{\sf Magnification=\dfrac{h'}{h}=-\dfrac{v}{u}}$

$\\ \sf\longmapsto \dfrac{h'}{h}=-\dfrac{v}{u}$

$\\ \sf\longmapsto \dfrac{4}{h}=-\dfrac{12}{3}$

$\\ \sf\longmapsto \dfrac{4}{h}=-4$

$\\ \sf\longmapsto h=\dfrac{-4}{4}$

$\\ \sf\longmapsto h=-1cm$

• It must be positive

$\\ \sf\longmapsto h=1cm$

$\\ \underline{\boxed{\sf{\therefore Height\:of\:object=1cm.}}}$

Answer 2

Answer:

16cm

Explanation:

u= -3cm

v=12cm

magnification=-v/u=-12/-3=4

also,magnification = H/h

h=4cm

=H/h=4

H/4=4

H=16