The current gain of a transistor in a common base
arrangement in 0.98 . Find the change in collector current corresponding to a
change of 5.0 mA in emitter current . What would be the change in base current?

Explanation

To solve the problem step by step, we will use the given information about the current gain of the transistor in a common base arrangement and the change in emitter current to find the changes in collector and base currents.

### Step 1: Understand the Current Gain
The current gain (α) in a common base configuration is given as 0.98. This means that for every unit of emitter current change, the collector current changes by 0.98 times that amount.

### Step 2: Use the Formula for Collector Current Change
The relationship between the change in collector current (ΔIc) and the change in emitter current (ΔIe) can be expressed as:
\[ \Delta I_c = \alpha \times \Delta I_e \]
Where:
- ΔIc = change in collector current
- α = current gain (0.98)
- ΔIe = change in emitter current (5.0 mA)

### Step 3: Calculate the Change in Collector Current
Substituting the values into the formula:
\[ \Delta I_c = 0.98 \times 5.0 \, \text{mA} \]
\[ \Delta I_c = 4.9 \, \text{mA} \]

### Step 4: Use the Relationship Between Emitter, Collector, and Base Currents
For any transistor, the relationship between the changes in emitter current, collector current, and base current is given by:
\[ \Delta I_e = \Delta I_b + \Delta I_c \]
Where:
- ΔIb = change in base current

### Step 5: Rearrange the Formula to Find Change in Base Current
Rearranging the equation to find ΔIb:
\[ \Delta I_b = \Delta I_e - \Delta I_c \]

### Step 6: Substitute the Known Values
Now substitute the known values:
\[ \Delta I_b = 5.0 \, \text{mA} - 4.9 \, \text{mA} \]
\[ \Delta I_b = 0.1 \, \text{mA} \]

### Final Answers
- Change in collector current (ΔIc) = 4.9 mA
- Change in base current (ΔIb) = 0.1 mA