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Red light has a wavelength greater than violet light. Therefore, the focal length of the lens for red light is greater than for violet light. Which of the following is correct?

1. f₁ > f₂
2. f₁ < f₂
3. f₁ = f₂
4. None of the above

Correct answer: f₁ > f₂

Solution

The focal length of a lens depends on the refractive index, which varies with wavelength. Red light has a longer wavelength and a lower refractive index compared to violet light, resulting in a greater focal length for red light.

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