A stick of length f/2 is placed on principal axis of a concave mirror of focal length f such that the image of one end coincides. then the length of its image will be

Question

asked Mar 28, 2022 114k views

1 Answer

Schrobe · Answer 1 · 2022-04-03T06:54:33+0000

look at the attachment

Radius of the culvature=2f

Now

Applying Mirror formula

$\\ \rm\longmapsto (1)/(v)-(1)/(u)=(1)/(f)$

$\\ \rm\longmapsto (1)/(v)=(1)/(u)+(1)/(f)$

$\\ \rm\longmapsto (1)/(v)=(1)/(-3f/2)+(-1)/(f)$

$\\ \rm\longmapsto (1)/(v)=-(2)/(3f)-(1)/(f)$

$\\ \rm\longmapsto (1)/(v)=(2-3)/(3f)$

$\\ \rm\longmapsto (1)/(v)=(-1)/(3f)$

$\\ \rm\longmapsto v=-3f$

Now

$\\ \rm\longmapsto m=(h')/(h)=-(v)/(u)=$

$\\ \rm\longmapsto m=(f)/(f/2)$

$\\ \rm\longmapsto m=2$