The focal length of the concave mirror is determined as 2.14 cm.
How to calculate the focal length of the mirror?
The focal length of the mirror is calculated by applying the following formula as shown below;
1/f = 1/u + 1/v
where;
- u is the object distance
- v is the image distance
- f is the focal length of the mirror
The given parameters include;
the object distance, u = 3 cm
object height = 2 cm
image height = 5 cm
The magnification is calculated as;
m = v/u = image height / object height
m = v/u = 5 / 2
m = v/3 = 2.5
v/3 = 2.5
v = 3 x 2.5
v = 7.5 cm
The focal length is calculated as follows;
1/f = 1/v + 1/u
1/f = 1/7.5 + 1/3
1/f = 0.4667
f = (1)/(0.4667)
f = 2.14 cm