An electron is accelerated through a potential difference of 144 V. The de-broglie wavelength associated would be approximately: |
10 nm 1 nm 0.1 nm 0.01 nm |
0.1 nm |
The correct answer is Option (3) → 0.1 nm The kinetic energy is also related, $K.E.=\frac{1}{2}mv^2$ $ev=\frac{1}{2}mv^2⇒v=\sqrt{\frac{2ev}{m}}$ $v=\sqrt{\frac{2ev}{m}}=\sqrt{\frac{2×1.6×10^{-19}×144}{9.11×10^{-31}}}$ $≃7.12×10^6$ Using the Momentum formula, $P=mv=(7.12×10^6)×(9.11×10^{-31})=6.48×10^{-24}$ Wavelength, $λ=\frac{h}{P}=\frac{6.63×10^{-34}}{6.48×10^{-24}}$ $=0.1nm$ |