Question

the focal length of a concave mirror is 15 cm if the object distance is 60 cm find the image distance .(ans u =-20cm)​

Answer 1

Answer:

-30 cm

Explanation:

Solution:

Given:

➜ If the focal length of a concave mirror is 15 CM if an object is placed at a distance of 30 cm.

Find:

➜ From the pole then its image will be formed at which.

Find:

➜ Find the image distance of the mirror.

According to the given question:

➜ -15 cm = focal length.

➜ -30 = object distance.

Formula used:

➜ 1/f = 1/v + 1/u

Know terms:

➜ initial velocity (u)

➜ final velocity (v)

➜ focal length (f)

Adding values in the formula:

➜ 1/f = 1/v + 1/u

➜ 1/-15 = 1/v - 1/30

➜ -1/15 + 1/30 = 1/v

➜ -2 + 1/30 = 1/v

➜ -1/30 = 1/v

➜ v = -30 cm

Therefore, -30 cm is the image distance of the mirror.

Or else you can refer to the attatchment given below

Answer 2

Answer:

i/f=1/q+1/p

1/q=1/f-1/p

1/q=1/15-1/60

1/q=4-1/60. taking l.c.m

1/q=3/60

1/q=1/20

q=20cm