The speed of an electromagnetic wave is equal to the product of its wavelength and its frequency.

Here's the formula:

Speed (c) = Wavelength (λ) * Frequency (f)

Where:

* c is the speed of light (approximately 299,792,458 meters per second)

* λ is the wavelength (measured in meters)

* f is the frequency (measured in Hertz, or cycles per second)