JEE Mains · Physics · STD 12 - Semicondutor electronics
- JEE Mains 2022
- Hard
- Numerical
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 \(6.0 \times 10^{5} \,ms ^{-1}\). The speed with which electron enters the \(p\) side will be \(\frac{x}{3} \times 10^{5} \,ms ^{-1}\) the value of \(x\) is .............. (Given mass of electron \(=9 \times 10^{-31} \,kg\), charge on electron \(=1.6 \times 10^{-19} \,C\).)
Pick an option to check your answer.
Answer & Solution
Correct Answer
(C) \(14\)
Step-by-step Solution
Detailed explanation
Work done by Electric field \(=K_{ r }- K _{ I }\)
\(\frac{1}{2} mv ^{2}-\frac{1}{2} mu ^{2}=-1.6-10^{-19} \times 0.4\)
\(\frac{1}{2} 9 \times 10^{-31}\left( v ^{2}- u ^{2}\right)=-0.64 \times 10^{-19}\)
\(u ^{2}- v ^{2}=\frac{2 \times 0.64 \times 10^{12}}{9}\)
\(v ^{2}=\left(36-\frac{128}{9}\right) \times 10^{10}\)
\(v =\frac{14}{3} \times 10^{5} \,m / s\)
\(x =14\)
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