A wave has frequency f = 4 Hz and wavelength λ = 12 m in a medium. What is the wave speed c?

A wave has frequency f = 4 Hz and wavelength λ = 12 m in a medium. What is the wave speed c?

• A. 24 m/s
• B. 60 m/s
• C. 8 m/s
• D. 48 m/s

Answer: (D)

The wave speed is found by multiplying frequency by wavelength: c = fλ. This works because frequency tells how many cycles pass each second and wavelength tells how far the wave travels in one cycle, so the product gives distance per unit time. With f = 4 s⁻¹ and λ = 12 m, c = 4 × 12 = 48 m/s. The units work out as meters per second (m/s), confirming the result. Other values would not match the product fλ, so they’re not correct.

The wave speed is found by multiplying frequency by wavelength: c = fλ. This works because frequency tells how many cycles pass each second and wavelength tells how far the wave travels in one cycle, so the product gives distance per unit time.

With f = 4 s⁻¹ and λ = 12 m, c = 4 × 12 = 48 m/s. The units work out as meters per second (m/s), confirming the result. Other values would not match the product fλ, so they’re not correct.