curved mirror notes

POINTS TO REMEMBER
FOR THE NUMERICALS ON SPHERICAL MIRROR . 1.THE OBJECT IS PLACED
IN FRONT OF THE REFLECTING SURFACE OF THE MIRROR.
2.ALL THE DISTANCES ARE TO BE MEASURED FROM THE POLE (P).
3. THE OBJECT DISTANCE (U) IS NEGATIVE.
4.THE IMAGE DISTATIVE EXCEPT WHEN THE OBJECT IS BETWEEN THE POLE
AND THE FOCUS AS THE IMAGE IS FORMED BEHIND THE MIRROR.
CORRECTION IN THE POINT 4
THE FIRST LINE READ
THE IMAGE DISTANCT IS NEGATIVE EXCEPT......
5) THE MAGNIFICATION IS =--V/U
THE SIZE OF THE IMAGE=MAGNIFICATION X SIZE OF THE OBJECT.
1) An object of height 12) m
=--24m
2) An object 50cm.At what distance from the mirror should a
screen be placed to get a sharp image and what will be size of
the image?
Using 1/v = 1/f --1/u
1/v =1/--15---1/--20
1/--15+1/20
---1/60
v=--60 cm
Magnification = --v/u=60/--20= --3
Size of the image =--3(5)
=--15cm
[4:01 PM, 4/1/2022] Old Man: 3) A 2 cm high object is placed at a
distance of 20 cm from a concave mirror. A real image is formed
at 40 cm from the mirror. Find the focal length of the mirror.
u=--20 cm ; v= --40 cm
1/f= 1/v + 1/u
=(1/--40) + (1/--20)
= 1/1333 cm.
[4:01 PM, 4/1/2022] Old Man: 4) Find the position of an object
which when placed in front of a concave mirror of focal length 10
cm a virtual image which is twice the size of the object.
magnification= --v/u
2=--v/u
Therefore v=--2u.
Now 1/u = 1/f --1/v
1/u +1/v =1/f
1/u + 1/--2u =1/f
--1/2u=1/10
u =--5 cm.