An object is placed on the principal axis of a convex lens of focal length 10 cm. If the distance of the object from the lens is 30 cm. What is the distance of the image formed?

Answer: Option B

First, let's identify what we know:
* Focal length (f) = 10 cm This tells us how strongly the lens bends light.
* Object distance (u) = 30 cm This is the distance between the object and the lens. Remember to use the sign convention! For a convex lens, u is usually taken as negative. So, u = -30 cm
We need to find:
* Image distance (v) = ? This is the distance between the image and the lens. This is what we want to calculate.
Now, let's use the lens formula:
1/f = 1/v - 1/u
Plug in the values:
1/10 = 1/v - 1/(-30)
1/10 = 1/v + 1/30
Now, let's solve for 1/v:
1/v = 1/10 - 1/30
1/v = (3 - 1)/30
1/v = 2/30
1/v = 1/15
Therefore, v = 15 cm
So, the correct answer is Option B: 15 cm