Answer:
45 cm
Explanation:
Formula = h' u / h = v
- v = (1.5) (-15) / 1
- v = - 22.5
v = 22.5
The image is positive, therefore it is a virtual and erect image.
∴ the image is formed at a distance of 22.5 cm behind the mirror.
1 / v + 1 / u = 1 / f
1 / f = 1 / 22.5 + 1 / (- 15)
1 / f = 1 / 22.5 -1 / 15
1 /f = (15 - 22.5) / 337.5
1 / f = -7.5 / 337.5
f = 337.5 / - 7.5
f = - 45 cm
∴ the focal length of the mirror is 45 cm.
