$A$ $200 \ g$ golf ball is moving with a speed of $5 \ m$ per hour. The associated wavelength is $(h = 6.625 \times 10^{-34} \ J \ s)$.

What is the de Broglie wavelength of a tennis ball weighing $66 \ g$ moving with a velocity of $10 \ m/s$?

The de Broglie wavelength of an electron in the $4^{th}$ Bohr orbit is (in $\pi a_{0}$)

The wavelength of an electron in the first orbit of a hydrogen atom is $3.3 \times 10^{-10} \ m$. The kinetic energy of the electron (in $J$) is:
$(h = 6.6 \times 10^{-34} \ Js, m_{e} = 9.0 \times 10^{-31} \ kg)$

Wavelength of $H^{+}$ ion with kinetic energy $1.65 \ eV$ is (mass of proton $= 1.6726 \times 10^{-27} \ kg$) (in $nm$)

The condition for a stable wave in an orbit of radius $r$ is given by the de Broglie relationship where the circumference of the orbit must be an integral multiple of the wavelength.