Question

define the term magnification as referred to spherical mirrors. if a concave mirror form a real image 40cm from the mirror ,when the object is placed at a distance of 20cm from its pole,find the focal length of the mirror.

Answer 1

The height of image with respect to height of object is known as magnification

Using mirror formula,
1/v+1/u=1/f
1/-40-1/20=1/f
-3/40=1/f
f= -40/3

Answer 2

Answer:

The focal length of the concave mirror is –13.33cm.

Explanation:

The enlargement of the picture created by spherical mirrors in relation to the size of the object is known as magnification. It is represented by the symbol m and represents the height-of the image tothe height of height ratio.

Given -

v, distance of image from mirror =–40cm

u, Distance of object from mirror= –20cm

To find - Focal length of mirror

Step by step explanation

Formula-1/f=1/v+1/u

1/f= 1/(-40)+1/(-20)

1/f= –1/40–1/20

1/f=–3/40

f=–40/3

f=–13.33cm

So the focal length of the concave mirror is –13.33cm.

20 cm is the distance between the object and the concave mirror. In this instance, the concave mirror's focal length is negative and equals 13.33 cm.

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