Explain how a prism separates white light into its constituent colors, mentioning the role of refractive index.
Answer
Because the refractive index of glass depends on wavelength, shorter wavelengths are refracted more, spreading white light into a spectrum.
Step-by-step solution
- A prism is made of glass whose refractive index varies with wavelength.
- When white light enters the prism, each wavelength experiences a different refraction angle.
- Shorter wavelengths (blue) have a higher refractive index and bend more than longer wavelengths (red).
- The beam therefore spreads into a spectrum with colors from violet to red.
Common mistake: Ignoring wavelength dependence of refractive index
Concept tested: Dispersion of light in prisms
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