Question

An object of height 2cm is placed at a distance of 15 cm from a concave mirror of focal length 10cm. Draw a scale diagram to locate the image. From the diagram, find the length of the image formed.

Answer 1

ho= 2cm
f= -10cm (concave)
u= -15cm
v=?

$\frac{1}{f} = \frac{1}{v} + \frac{1}{u} \\ \frac{1}{ -10} = \frac{1}{v} + \frac{1}{ - 15} \\ \frac{1}{v} = \frac {1}{ - 10} + \frac{1}{15} \\ \frac{1}{v} = \frac{ - 3 + 2}{30} \\ \frac{ 1}{v} = \frac{ - 1}{30} \\ \\ v = - 30cm\\\ m = \frac{ - v}{u} = \frac{hi}{ho} \\ m = \frac {- (- 30)}{ - 15} = \frac{hi}{1} \\ m = - 2 \\ hi = - 2$
Nature of image: real and inverted
Size of image: dimnished
Position of image: infinity