Question

A 4 cm high candle flame is placed at a distance of 20 cm from a screen. On placing a concave mirror exactly double its distance a distinct image is formed on the screen. what is the focal lenght of the mirror and the size of the image formed. draw a diagram to show the image formation.

Answer 1

Hii.... I don't know the answer

Answer 2

Given :

object height= ho= =4cm

object distance = u= -20cm[ after sign conventions]

image distance =v=-40cm

f=?

by mirror formula :

1/f=1/v+1/u

= -1/40 - 1/20

=-1-2/40

=-3/40

f= -40/3

f=- 13.3 m

magnification=m= -v/u= hi/ho

m= -(-40) / -20

= - 2 So image formed is magnified, real and inverted .

hi=mxh0

=-2x4

=-8cm

So when an object is placed between f and  C . image will be formed beyond c.

Refer the attachment   for ray diagram :