Question

An electron is accelerated through a potential difference of 1000 V. Its velocity is nearly

• A. $ 3.8\,\times {{10}^{7}}m/s $
• B. $ \text{1}\text{.9 }\!\!\times\!\!\text{ 1}{{\text{0}}^{6}}\text{m/s} $
• C. $ \text{1}\text{.9 }\!\!\times\!\!\text{ 1}{{\text{0}}^{7}}\text{m/s} $
• D. $ \text{5}\text{.7 }\!\!\times\!\!\text{ 1}{{\text{0}}^{7}}\text{m/s} $

Answer 1

Answer: (C)

If the voltage given is $ V $ , then the energy of electron $ =\frac{1}{2}m{{v}^{2}}=eV $ $ v=\sqrt{\frac{2eV}{m}} $ $ =\sqrt{\frac{2\times 1.6\times {{10}^{-19}}\times 1000}{9.1\times {{10}^{-31}}}} $ $ =1.875\times {{10}^{7}} $ $ =1.9\times {{10}^{7}}\,\,m/s $