In a transistor, the value of $\alpha$ varies between $\frac{20}{21}$ and $\frac{100}{101}$. Then the value…

In a transistor, the value of $\alpha$ varies between $\frac{20}{21}$ and $\frac{100}{101}$. Then the value of $\beta$ varies between
  1. 1 and 10
  2. 0.95 and 0.99
  3. 20 and 100
  4. 200 and 300

Solution

Given, in a transistor current gain, $ \alpha=\frac{20}{21} \text { and } \frac{100}{101} $ Now, common emitter transistor DC current gain, $\beta=\frac{\alpha}{1-\alpha}$ Case I If $\alpha=\frac{20}{21}$, then $\beta=\frac{\frac{20}{21}}{1-\frac{20}{21}}=20$ Case II $\alpha=\frac{100}{101}$, then $\beta=\frac{\frac{100}{101}}{1-\frac{100}{101}}=100$ $\therefore$ Value of $\beta$ varies between, $\beta \in[20,100]$

Asked in: AP EAMCET 2019 (20 Apr Shift 2)

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