(a) An object is placed just outside the principal focus of concave mirror. Draw a ray diagram to show how the image is formed, and describe its size, position and nature.
(b) If the object is moved further away from the mirror, what changes are there in the position and size of the image?
(c) An object is 24 cm away from a concave mirror and its image is 16 cm from the mirror. Find the focal length and radius of curvature of the mirror, and the magnification of the image.
(a) figure.png
The image is real, inverted and magnified. It is formed beyond the centre of curvature of the mirror.
(b) If the object is moved further away from the mirror, the image is formed nearer to the mirror and its size goes on decreasing.
(c) u = -24 cm
v = -16 cm
f = ?, R = ?, m = ?
We know that
\(\frac{1}{v}\) + \(\frac{1}{u}\) = \(\frac{1}{f}\)
\(\frac{1}{-16}\) + \(\frac{1}{-24}\) = \(\frac{1}{f}\)
\(\frac{-5}{48}\) = \(\frac{1}{f}\)
f = -9.6 cm
R = 2f
= 2 x -9.6 = -19.2 cm
We know that
m = -\(\frac{v}{u}\)
m = -\(\frac{-16}{-24}\)
m = -0.666