Question

Why de broglie waves associated with a moving football are not visible?

Answer 1

Wavelength of the object can only be observed when the wavelength is comparable to the size of the object.

De-broglie wavelength is given by : $\lambda$ = h/mv

where m is the mass of the object.
h = planks' constant =6.66×10^-34 js
Since wavelength is inversely proportional to the mass of the object which is too large and h is also very small therefore wavelength will be very small compared to the size of the object.

Hence wavelength of the moving ball can not be seen.