Question

A spherical mirror produces an Image of magnification -1 on a screen placed at a distance of 50cm from the mirror.
a]write the type of mirror.
b]find the distance of the image from the object
C] what is focal length of the mirror
d] draw the ray diagram to show the image formation in this case​

Answer 1

Explanation:

Given : magnification = –1

Image distance = 50 cm

(a) Since, the magnification is negative therefore the image formed is real and inverted.

so , v = -50 cm

magnification is given by,

m = - v/u

-1 = -(-50)/u

-1 = 50/u

u = - 50 cm

So , As formation of image is on screen and is a real image .

Therefore, the mirror will be concave mirror.

(b) Since , the distance of image from the mirror is – 50 cm.

(c) 1/f = 1/v + 1/u

1/f = 1/-50 + 1/-50

1/f = – 2/50

1/f = – 1/25

f = -25 cm

Therefore, the focal length of the mirror is f = -25cm.