A virtual image three times the size of the object is obtained with a concave mirror of radius of curvature 36 cm. The distance of the object from the mirror is
Given:
Magnification (m) = 3 (virtual image is erect).
Radius of the curvature, R =36 cm
Focal Length (f) = = -18cm (Negative for concave mirror).
Now by formula,
1. Magnification,
Where,
v is the image distance,
u is the object distance,
Putting the values in the above formula, we get
⇒
2. Mirror formula
Where
f is the focal length of the mirror
v is the image distance from the mirror
u is the object distance from the mirror
Thus, putting the values in the equation, we get
Thus, on solving the above equation, we get
u=-12 cm
Hence the distance of the object from the mirror is 12 cm.