Calculate the momentum of a particle which has a wavelength of $1 \ \mathring{A}$.

Two base balls (masses: $m_1 = 100 \ g$ and $m_2 = 50 \ g$) are thrown. Both of them move with uniform velocity,but the velocity of $m_2$ is $1.5$ times that of $m_1$. The ratio of de Broglie wavelengths $\lambda(m_1) : \lambda(m_2)$ is given by

Calculate the wavelength of an electron if its mass is $9.1 \times 10^{-31} \, kg$,its velocity is $1/10$ of the speed of light,and the value of Planck's constant $h$ is $6.626 \times 10^{-34} \, J \cdot s$.

Which one of the following explains light both as a stream of particles and as wave motion?

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:
$(h = 6.6 \times 10^{-34} \ Js, m_{e} = 9.0 \times 10^{-31} \ kg)$

The $K.E.$ of an electron is $4.55 \times 10^{-25} \,J$. Calculate its $\lambda$.