A double convex lens has a radius of curvature of 20 cm on both sides. What is i

₹0.0

Question: A double convex lens has a radius of curvature of 20 cm on both sides. What is its focal length if the refractive index is 1.5?

Options:

Correct Answer: 10 cm

Solution:

Using the lens maker\'s formula, f = R/(n-1), we find f = 20/(1.5-1) = 40 cm.

A double convex lens has a radius of curvature of 20 cm on both sides. What is its focal length if the refractive index is 1.5?

A double convex lens has a radius of curvature of 20 cm on both sides. What is its focal length if the refractive index is 1.5?

Step 1: Understand that we are using the lens maker's formula, which is f = R / (n - 1).
Step 2: Identify the values we have: the radius of curvature (R) is 20 cm and the refractive index (n) is 1.5.
Step 3: Substitute the values into the formula: f = 20 / (1.5 - 1).
Step 4: Calculate the denominator: 1.5 - 1 = 0.5.
Step 5: Now substitute this value back into the formula: f = 20 / 0.5.
Step 6: Perform the division: 20 divided by 0.5 equals 40.
Step 7: Conclude that the focal length (f) of the lens is 40 cm.

Lens Maker's Formula – The formula used to calculate the focal length of a lens based on its radii of curvature and refractive index.
Refractive Index – A measure of how much light bends when entering a material, crucial for determining the focal length.
Radius of Curvature – The distance from the lens surface to its center of curvature, affecting the lens's optical properties.