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# De-Broglie proposed dual nature for electron by putting his famous equation $\lambda = \large\frac{h}{mu}$. Later on Heisenburg proposed uncertainity principle as $\bigtriangleup p .\bigtriangleup x \geq \large\frac{h}{2}(h = \large\frac{h}{2\pi})$ . On the contrary particle nature of electron was established on the basis of photoelectric effect. When a photon strikes the metal surface , it gives up its energy to the electron. Part of this energy (say w) is used by the electron to escape from the metal and the remaining imparts the kinetic energy $\large\frac{1}{2}mu^2$ to the photoelectron. The potential applied on the surface to reduce the velocity of photoelectron to zero is known as stopping potential. The wavelength of a golf ball weighing 200g and moving at a speed of 5meter/hr is of the order:

$(a)\;10^{-10}m\qquad(b)\;10^{-20}m\qquad(c)\;10^{-30}m\qquad(d)\;10^{-40}m$

$\lambda = \large\frac{h}{mu}$
$=\large\frac{6.6\times10^{-34}\times3600}{200\times10^{-3}\times5}$
$=2.376\times10^{-30}$

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