A real image of an object formed by a converging lens of focal lenght 15cm is 3 times the size of the object. What is the distance of the object ftom the lens

Answer 1

To solve this problem, we can use the lens formula:

1/f = 1/v - 1/u

Where:
- f is the focal length of the lens
- v is the image distance from the lens
- u is the object distance from the lens

Given:
- f = 15 cm
- The image is 3 times the size of the object, which means the magnification (m) is 3.

We know that magnification (m) is given by the formula:

m = -v/u

Rearranging the equation, we get:

v = -m * u

Substituting the given values, we get:

-3 = -v/u
3 = v/u

Plugging this into the lens formula, we get:

1/15 = 1/3 - 1/u

Multiplying through by 15u, we get:

u = 15u/3 - 15

Simplifying, we get:

u = 5u - 15

Rearranging the equation, we get:

4u = 15

Dividing by 4, we get:

u = 15/4

So, the distance of the object from the lens is 15/4 cm.