Question

If an object is placed at 10 cm in front of a concave mirror of focal length 15 cm then the position of image is

Answer 1

Given:-

• Object distance ,u = -10cm

• Focal length ,f = 15cm

To Find:-

• Position of Image ,V

Solution:-

The Focal length of concave mirror is taken as positive while the Focal length of Convex mirror is taken as negative . Object distance always be taken as negative.

Using Mirror Formula

• 1/v + 1/u = 1/f

Substitute the value we get

➺ 1/v +1/(-10) = 1/15

➺ 1/v - 1/10 = 1/15

➺ 1/v = 1/15 + 1/10

➺ 1/v = 2+3/30

➺1/v = 5/30

➺ 1/v = 1/6

➺ v = 6/1

➺ v = 6cm

Therefore, the image is formed 6 cm from the object.

Here, the position of the image is same side as the object is placed . The image formed is real and Inverted .

Answer 2

Use mirror formula.

• 1/v + 1/u = 1/f

Substituting the value we get

==> 1/v +1/(-10) = 1/15

==> 1/v - 1/10 = 1/15

==> 1/v = 1/15 + 1/10

==> 1/v = 2+3/30

==> 1/v = 5/30

==> 1/v = 1/6

==> v = 6/1

==> v = 6cm

The image forms 6 cm from the object.

Here, the position of the image is same side as the object is placed . The image formed is real and Inverted .