MHT CET · Physics · Semiconductors
In an n-p-n transistor, the collector current is \(28 \mathrm{~mA}\). If \(80 \%\) of electrons reach the collector, its base current in \(\mathrm{mA}\) is
- A 35
- B 24
- C 14
- D 7
Answer & Solution
Correct Answer
(D) 7
Step-by-step Solution
Detailed explanation
It is given that \(80 \% \mathrm{I}_{\mathrm{e}}=\mathrm{I}_{\mathrm{c}}=28 \mathrm{~mA}\)
\(\therefore \frac{80}{100} \mathrm{I}_{\mathrm{e}}=28 \mathrm{~mA} \Rightarrow \mathrm{I}_{\mathrm{e}}=35 \mathrm{~mA} \)
\( \text {But, } \mathrm{I}_e=\mathrm{I}_{\mathrm{c}}+\mathrm{I}_{\mathrm{B}} \)
\( \therefore \mathrm{I}_{\mathrm{B}}=\mathrm{I}_{\mathrm{e}}-\mathrm{I}_{\mathrm{c}} \Rightarrow \mathrm{I}_{\mathrm{B}}=35-28=7 \mathrm{~mA}\)
\(\therefore \frac{80}{100} \mathrm{I}_{\mathrm{e}}=28 \mathrm{~mA} \Rightarrow \mathrm{I}_{\mathrm{e}}=35 \mathrm{~mA} \)
\( \text {But, } \mathrm{I}_e=\mathrm{I}_{\mathrm{c}}+\mathrm{I}_{\mathrm{B}} \)
\( \therefore \mathrm{I}_{\mathrm{B}}=\mathrm{I}_{\mathrm{e}}-\mathrm{I}_{\mathrm{c}} \Rightarrow \mathrm{I}_{\mathrm{B}}=35-28=7 \mathrm{~mA}\)
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