
Speed = Frequency × Wavelength

Let's put this new formula to good use by looking at a few more examples:
 Bill counts 5 waves on a pond in 10 s. The distance between them is 80 cm. What is their speed?
 Lizi reads the back label of her microwave oven. It says frequency = 2,450 MHz. The speed of microwaves is 3.00×10^{8} m/s.
What wavelength are they?
 Paul plays a note of wavelength 25 cm on his synthesiser.
He knows the speed of sound is 340 m/s in air. What is its frequency?

Have a go at answering these questions on a piece of paper, then click below for the answers.
