Visible light spectrum properties

Steps:

• Visible light ranges from red (longer wavelength, lower frequency) to violet (shorter wavelength, higher frequency).
• Wavelength λ and frequency f relate by c = f λ, where c is constant speed in vacuum.
• In a prism, dispersion causes violet light to deviate more than red due to wavelength-dependent refractive index.
• All electromagnetic waves travel at speed c in vacuum, independent of wavelength.

Why B is correct:

• In the electromagnetic spectrum, frequency increases from red to violet, so red has lower frequency than violet.

Why the others are wrong:

• A: A prism deviates violet light more than red light due to higher refractive index for shorter wavelengths.
• C: Red light has a longer wavelength than violet light.
• D: The speed of all light in vacuum is the same constant c.

Final answer: B