Question

The property of light that explains the formation of coloured images due to thick lenses is

• A. Refraction
• B. Dispersion
• C. Reflection
• D. Total internal reflection

Hint:

Chromatic aberration is caused by Dispersion. Spherical aberration is caused by the geometry (aperture size) of the lens.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The formation of coloured images (defects) by lenses is called Chromatic Aberration. This occurs because the focal length of a lens depends on the refractive index ($f \propto \frac{1}{\mu-1}$). Since the refractive index $\mu$ varies with wavelength (color) of light, different colors focus at different points.
Step 2: Identifying the Property:
The phenomenon where refractive index depends on wavelength, causing splitting of white light into constituent colors, is called Dispersion.