Question

Red light has a longer wavelength than green light which has a longer wavelength than blue light which has a longer wavelength than violet light.
When white light passes through a diffraction grating, which order is "bent" by diffraction the most?

• A. Red
• B. Green
• C. Blue
• D. Violet
• E. All colors "bend" the same

Answer 1

Answer: (A)

Red

Using $bsin\theta =n\lambda$

$\therefore$ $\theta =si{n}^{-1}(\frac{n\lambda }{b})$ $⟹\theta \propto \lambda$

Given : ${\lambda }_{red}>{\lambda }_{green}>{\lambda }_{blue}>{\lambda }_{violet}$

$⟹$ ${\theta }_{red}>{\theta }_{green}>{\theta }_{blue}>{\theta }_{violet}$

Hence the red light bends the most.