An object is placed at 40 cm from a concave mirror of focal length 30 cm. The image is
Solution:
Given:
Object distance, u = -40 cm (according to the sign convention for mirrors, object is placed to the left)
Focal length of concave mirror, f = -30 cm (focal length of a concave mirror is negative)
Using the mirror formula:
1/f = 1/v + 1/u
Rearranging to solve for image distance (v):
1/v = 1/f - 1/u
1/v = 1/(-30) - 1/(-40)
1/v = -1/30 + 1/40
To combine the fractions, find a common denominator, which is 120:
1/v = (-4/120) + (3/120)
1/v = (-4 + 3) / 120
1/v = -1/120
v = -120 cm
The negative sign for 'v' indicates that the image is formed on the same side as the object (in front of the mirror), which means it is a real image. Real images formed by mirrors are always inverted.
Now, let's calculate the magnification (m) to determine the size and orientation of the image:
m = -v/u
m = -(-120 cm) / (-40 cm)
m = 120 / (-40)
m = -3
The negative sign for 'm' confirms that the image is inverted.
The magnitude of magnification |m| = 3, which is greater than 1. This indicates that the image is enlarged.
Therefore, the image formed is Real, Inverted, and Enlarged.