For electrons

PHYSICS · Single correct · A Level · Physics · Particles and radiation · Particles and radiation

Problem

For electrons, a graph of de Broglie wavelength

\lambda

(in m) versus

1/\sqrt{V}

(in V

^{-1/2}

) is drawn, where

V

is the accelerating potential. The experimental slope of the straight line is measured to be

1.20\times10^{-9}\,\text{m\,V}^{1/2}

. Taking electron mass

m_e = 9.11\times10^{-31}\,\text{kg}

and charge

e = 1.60\times10^{-19}\,\text{C}

, which of the following values is closest to the Planck constant obtained from this experiment? (a)

3.2\times10^{-34}\,\text{J\,s}

(b)

6.5\times10^{-34}\,\text{J\,s}

(c)

9.8\times10^{-34}\,\text{J\,s}

(d)

4.6\times10^{-34}\,\text{J\,s}