A wave has frequency 20 Hz and wavelength 5 m. What is its speed?

A wave has frequency 20 Hz and wavelength 5 m. What is its speed?

• A. 25 m/s
• B. 100 m/s
• C. 200 m/s
• D. 15 m/s

Answer: (B)

The speed of a wave is found by multiplying its frequency by its wavelength: v = fλ. Here, the frequency is 20 Hz (20 cycles per second) and the wavelength is 5 m (distance per cycle). So the speed is 20 × 5 = 100 m/s. This matches the idea that each second, 20 cycles pass, and each cycle corresponds to 5 meters of travel, giving 100 meters per second. The other numbers would come from using an incorrect relationship between f and λ, which isn’t the case here.

The speed of a wave is found by multiplying its frequency by its wavelength: v = fλ. Here, the frequency is 20 Hz (20 cycles per second) and the wavelength is 5 m (distance per cycle). So the speed is 20 × 5 = 100 m/s. This matches the idea that each second, 20 cycles pass, and each cycle corresponds to 5 meters of travel, giving 100 meters per second. The other numbers would come from using an incorrect relationship between f and λ, which isn’t the case here.