Question

An object is placed at a distance of 30 cm from the optical centre of a concave lens of focal length 15 cm. Use lens formula to determine the distance of the image from the optical centre of the lens.

Answer 1

To determine the distance of the image from the optical center of the concave lens using the lens formula, we can use the equation:

`1/f = 1/v - 1/u`

Where:

• f is the focal length of the concave lens (given as −15 cm since it's concave).
• v is the ·distance of the image from the optical center of the lens (what we want to find)
• u is the distance of the object from the optical center of the lens (given as −30 cm since it's on the opposite side of the direction of the incident light)

Now, let's substitute the given values into the lens formula and solve for v :

`1/(-15) = 1/v - 1/(-30)`

First, let's simplify the equation:

`(-1)/15 = 1/v + 1/30`

Now, let's find the common denominator:

`(-3)/30 = 1/v`

Now, we can solve for `u`:

`1/v = (-3)/30`

`v = 30/(-3)`

`v = -10` cm

So, the distance of the image from the options center of the concave lens is −10 cm.