A potential barrier of 0.4 V exists across a p-n junction. An electron enters the junction from the n-side with a speed of 6.0 $\times$ 105 ms$-$1. The speed with which electron enters the p side will be ${x \over 3} \times {10^5}$ ms$-$1 the value of x is _____________.
(Given mass of electron = 9 $\times$ 10$-$31 kg, charge on electron = 1.6 $\times$ 10$-$19 C.)
Answer (integer)
14
Solution
<p>Conserving energy,</p>
<p>${1 \over 2}m{v^2} = {1 \over 2}m{(6 \times {10^5})^2} - 0.4\,eV$</p>
<p>$$ \Rightarrow v = \sqrt {{{(6 \times {{10}^5})}^2} - {{2 \times 1.6 \times {{10}^{ - 19}} \times 0.4} \over {9 \times {{10}^{ - 31}}}}} $$</p>
<p>$= \sqrt {36 \times {{10}^{10}} - {{1.28} \over 9} \times {{10}^{12}}}$</p>
<p>$\Rightarrow v = {{14} \over 3} \times {10^5}$ m/s</p>
<p>$\Rightarrow x = 14$</p>
About this question
Subject: Physics · Chapter: Electronic Devices · Topic: p-n Junction Diode
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