Disperson of white light is the ability of white light to

Analyze the question: It asks what "dispersion" of white light means. Look at the key word: dispersion means to spread out or separate.

Explain the concept: White light is not a single colour. It is a mixture of seven colours: red, orange, yellow, green, blue, indigo and violet (ROYGBIV). Each colour has a different wavelength, so each is bent (refracted) by a different amount when it passes through a medium such as a glass prism or water droplets. Red bends the least and violet bends the most. This spreads the white light into a band of colours called a spectrum.

Solution, checking each option:

• A. Penetrate air, water and glass: This is about transmission of light through media. It is not dispersion.
• B. Move in a straight line: This is rectilinear propagation of light, which explains shadows and the pinhole camera. It is not dispersion.
• C. Move around corners: This describes diffraction, the bending of waves around obstacles. It is not dispersion.
• D. Separate into its component colours: This is the definition of dispersion. A prism splits white light into the spectrum, and a rainbow forms the same way, with raindrops acting as tiny prisms.

Answer: D.

Tip: Link the word to its meaning: DISpersion sounds like "dis-perse", which means to scatter or separate. Whenever you see dispersion in light, think "splitting into colours". Don't confuse it with diffraction (bending around corners) or reflection and refraction.