# Waves frequency and speed

Frequency is how many waves passes a certain point in a second and speed is how fast the wave is travelling. Surely this means they are directly proportional as if the speed is high that means lots of waves are passing a point in a certain amount of time ie frequency is larger?

And so looking at the wave equation

V= f x wavelength
how can frequency ever remain constant when speed increases. And so when looking at refraction, my textbook says that when the speed of a wave increases and frequency is constant, wavelength increases. How is it possible for frequency to remain constant?
Thanks
Original post by M.H4kim
Frequency is how many waves passes a certain point in a second and speed is how fast the wave is travelling. Surely this means they are directly proportional as if the speed is high that means lots of waves are passing a point in a certain amount of time ie frequency is larger?

And so looking at the wave equation

V= f x wavelength
how can frequency ever remain constant when speed increases. And so when looking at refraction, my textbook says that when the speed of a wave increases and frequency is constant, wavelength increases. How is it possible for frequency to remain constant?
Thanks

Radio waves and light waves travel at the same speed. The wavelength of a radio wave could be hundreds or even a thousand meters but the wavelength of light would be something around 500 nm.

For a given light (or radio) source the frequency is fixed and the wavelength has to adjust depending on the speed of the wave through the material the wave finds itself in.

If you shine coloured light through a glass block and out the other side the light is the same colour cos the same number of waves per second is coming out as is going in, the waves just have to bunch peaks and troughs closer together when they're going at a slower speed in the glass.