A Level Physics Practice Exam

What describes the relation between frequency, wavelength, and speed of light?

1. Frequency and speed are independent

2. Wavelength is directly proportional to speed

3. Speed is the product of wavelength and frequency

4. Wavelength decreases with increasing speed

The correct answer is: Speed is the product of wavelength and frequency

The relation between frequency, wavelength, and speed of light is captured in the equation \( c = f \times \lambda \), where \( c \) is the speed of light, \( f \) is the frequency, and \( \lambda \) is the wavelength. This fundamental relationship indicates that the speed of light is equal to the product of its frequency and wavelength. When frequency increases, the wavelength decreases, assuming the speed of light remains constant, which is true in a vacuum. Hence, the product \( f \times \lambda \) gives the constant speed of light, which reinforces that the correct answer is indeed the statement about speed being the product of wavelength and frequency. This understanding aligns with principles of wave mechanics and highlights how light behaves as both a wave and a particle, maintaining a consistent speed in a vacuum regardless of its frequency or wavelength.