The object placed at varying distances from the focal point accounts for the change in focal length.
And the focal length of a concave mirror is 44 cm.
What is focal length?
When a mirror or lens is placed at some distance from the focal point, then that distance is known as the focal length of the mirror or lens.
Given data:
The magnification of the image is, m = + 3.2.
The object distance is, u = 30 cm.
The expression for the magnification of the image is ,
\(m = \dfrac{v}{u}\)
Here,
v is the image distance.
Solving as,
\(3.2 = \dfrac{v}{30}\\\\v =3.2 \times 30\\\\v = 96 \;\rm cm\)
Now, using the mirror equation to calculate the focal length of the concave mirror is,
\(\dfrac{1}{f}=\dfrac{1}{v}+\dfrac{1}{u}\)
Solve by substituting the values as,
\(\dfrac{1}{f}=\dfrac{1}{96}+\dfrac{1}{30}\\\\\\\dfrac{1}{f}=\dfrac{30+96}{2880}\\\\f =44 \;\rm cm\)
Thus, we can conclude that the focal length of a concave mirror is 44 cm.
Learn more about the concave mirror here:
https://brainly.com/question/25937699
