Question

an object of height 6 cm is placed on the principal axis of a concave mirror of focal length f at a distance of 4 f. find the height and nature of the image?


Plz those who don't know the ans


Don't show ur mercy here...

Answer 1

It is a concave mirror so it is negative
Height of the object=6cm
Focal length =f=-f
Radius of curvature is =2*f (f)
=2f
Distance of the object =4f (u) =-4f
That means it is beyond the centre of curvature
Mirror formula:1/v+1/u =1/f
Sub in formula
1/v+-1/4f=-1/f
1/v=-1/f-1/4f
1/v=-4+1/4f
1/v=-3/4f
V=-4f/3
Height of the image = - (v/u) =hi/ho
-1/3=x/6
3x=-6
X=-2

Answer 2

Explanation:

1+v+(-1/4f)=-1f

1/v= -1/f-1/4f

1/v= -4+1/4f

1/v=-3/4f

v=-4f/3

hi/ho= -v/ u

-1/3=x/6

now cross multiply them ..

and it will be ....

3x= -6

x=-6/3

and the answer will be

x=-2