Question

21. The radius of curvature of a concave
mirror is 30 cm if the object placed at
10 cm from the mirror then the image is​

Answer 1

Given:-

• Radius of Curvature ,R = -30

• Object distance ,u = -10cm

To Find:-

• Image distance ,v

Solution:-

As we know that the relationship between Radius of Curvature and Focal length .

• f = R/2

Where

f is the focal length

R is the radius of Curvature

Substitute the value we get

→ f = -30/2

→ f = -15

focal length of mirror is -15 cm.

Now, 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 = 1/30

→ v = 30 cm

Therefore , the image distance is 30 cm .

Answer 2

Answer:

f = -30/2

→ f = -15

focal length of mirror is -15 cm.

Now, 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 = 1/30

→ v = 30 cm

Therefore , the image distance is 30 cm .