Hello! This quote is from my physics text book “ From the formula speed = lambda * Frequency we can conclude that the reduction in wavelength is because water travels with a slower speed in when moving from deep to shallow water” This does not make any sense at all. You can’t explain the change of any factor in a formula By the fact that the product of the factors have changed. I just mean that speed in this formula is directly dependent on the lambda and the frequency, while the wavelength and its frequency are not dependent of the speed, they rather determent it together. I think this explanation sucks. Do you agree? And if so, can you provide me with a better one on why the wavelength change when a water wave cross from depth to shallow water? I am counting on you guys.