Question

A current gain for a transistor working as CB amplifier is \(0.90\). If emitter current is \(10 \mathrm{~mA}\), then base current is (A) \(1 \mathrm{~m} \mathrm{~A}\) (B) \(2 \mathrm{~m} \mathrm{~A}\) (C) \(0.1 \mathrm{~mA}\) (D) \(0.2 \mathrm{~mA}\)

Short answer

The base current (I_B) is 1 mA, which corresponds to option (A).

Step-by-step solution

Identify given information

We are given: - Current gain (\( \alpha \)) for a transistor working as a CB amplifier = 0.90 - Emitter current (I_E) = 10 mA We need to calculate the base current (I_B).

Understand the relationship between emitter, base, and collector currents

For a transistor, the relationship between the emitter, base, and collector currents is given by: I_E = I_B + I_C In this case, we also have the current gain (\( \alpha \)), which is defined as the ratio of the collector current (I_C) to the emitter current (I_E). \( \alpha \) = I_C / I_E We can rearrange this equation to find I_C: I_C = \( \alpha \) * I_E

Calculate the collector current

Plugging in the given values: I_C = 0.90 * 10 mA = 9 mA

Calculate the base current

Now that we have the collector current, we can find the base current using the equation I_E = I_B + I_C: I_B = I_E - I_C = 10 mA - 9 mA = 1 mA So, the base current (I_B) is 1 mA, which corresponds to option (A).