Question

A 150 cm tall person was standing 200 cm in front of a huge concave mirror of focal length = 250 cm. How will his image appear in the mirror?​

Answer 1

Answer:

A person 1.80 m tall stands in front of a plane mirror. What is the minimum height of the mirror, and how high must its lower edge be above the floor for the person to be able to see his/her whole body? Person’s eyes are 6.0 cm below the top of the head.

Answer 2

Given: Height = 150cm

          Distance from concave mirror = 200cm

          Focal length = 250cm

To find: Appearance of image in the mirror

Solution:

• A person is standing between focal length and pole, therefore the image formed will be virtual, erect, and larger than that of an object.

• The image will be formed behind the mirror.

Now using the mirror formula, we can find the distance of the image

1/f = 1/u + 1/v ( where, f is the focal length, u is the object distance, v is the image distance)

1/250 = 1/200 + 1/v

1/v = 1/250 - 1/200

1/v = 1/1000

v = 1000/1cm = 1000cm

v = 1000cm

Linear magnification is the ratio of height of image to the height of object.

m = -v/u

   = - 1000/(200)

    = - 5

Now, as magnification is h'/h ( h' is the height of image, and h is the height of object)

-5 = h'/150

h' = - 5*150 = -750cm

Therefore, the height of the image will be 750cm and will form at 1000cm behind the mirror.