For a transistor

Question:

For a transistor $\alpha$ and $\beta$ are given as $\alpha=\frac{I_{C}}{I_{E}}$ and $\beta=\frac{I_{C}}{I_{B}} .$ Then the correct relation between $\alpha$ and $\beta$ will be :

  1. $\alpha=\frac{1-\beta}{\beta}$

  2. $\beta=\frac{\alpha}{1-\alpha}$

  3. $\alpha \beta=1$

  4. $\alpha=\frac{\beta}{1-\beta}$


Correct Option: , 2

Solution:

$\alpha=\frac{\mathrm{I}_{\mathrm{C}}}{\mathrm{I}_{\mathrm{E}}}, \beta=\frac{\mathrm{I}_{\mathrm{C}}}{\mathrm{I}_{\mathrm{B}}} ; \mathrm{I}_{\mathrm{E}}=\mathrm{I}_{\mathrm{C}}+\mathrm{I}_{\mathrm{B}}$

$\alpha=\frac{\mathrm{I}_{\mathrm{C}}}{\mathrm{I}_{\mathrm{C}}+\mathrm{I}_{\mathrm{B}}}=\frac{\mathrm{I}_{\mathrm{C}} / \mathrm{I}_{\mathrm{B}}}{\frac{\mathrm{I}_{\mathrm{C}}}{\mathrm{I}_{\mathrm{B}}}+1}=\frac{\beta}{\beta+1}+$

$1+\frac{1}{\beta}=\frac{1}{\alpha}$

$\frac{1}{\beta}=\frac{1-\alpha}{\alpha}$

$\beta=\frac{\alpha}{1-\alpha}$

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