Question

The focal length of a concave mirror is 30cm If the distance of the object from the pole in front of the
mirror so that a the real image three times the size of the object formed is 10x cm, find value of x is​

Answer 1

ANSWER
Given focal length f=30cm object length =30 cm and object distance u= 45 cm.
Thus from mirror formula we get ,
f
1
​
=
v
1
​
+
u
1
​

Here both focal length and object distance lies in front of the mirror so consider them negative,hence the above equation can written as
v
1
​
=
f
1
​
−
u
1
​

v
1
​
=
uf
u−f
​

v=
u−f
uf
​

v=−90
Also we know magnification m=
u
−v
​
=
h
o
​

h
i
​

​

10x=2×30
x=6cm