Question

For a transistor, the current ratio ${\alpha }_{dc}=\frac{69}{70}$. The current gain ${\beta }_{dc}$ is

• A. $66$
• B. $67$
• C. $69$
• D. $71$

Answer 1

Answer: (C)

As ${\beta }_{DC}=\frac{{\alpha }_{DC}}{1-{\alpha }_{DC}}\Rightarrow {\beta }_{DC}=\frac{69/70}{1-\frac{69}{70}}=\frac{69}{70-69}=69$