Question

The de Broglie wavelength associated with a ball of mass $150\,g$ travelling at $30\,m\,s^{-1}$ is

• A. $1.47 \times 10^{-34}\,m$
• B. $1.47 \times 10^{-16}\,m$
• C. $1.47 \times 10^{-19}\,m$
• D. $1.47 \times 10^{-31}\,m$

Answer 1

Answer: (A)

Mass of the ball, $m=150\,g=0.15\,kg$,
Speed of the ball, $v=30\,m\,s^{-1}$
Momentum, $p = mv =0.15\times30=4.5\,kg\,m\,s^{-1}$ de Broglie wavelength,
$\lambda=\frac{h}{p}=\frac{6.63\times10^{-34}}{4.5}$
$=1.47\times10^{-34}\,m$