Question

an object of 1 cm produce areal image of 1.5.cm of high when placed at adistance of 15cm from concave mirror calculate the position of the image and the focal lenght of the concave mirror​

Answer 1

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.