Define current gain in C-B amplifier.

Explanation

To define the current gain in a common base (C-B) amplifier, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Common Base Amplifier**:
- A common base amplifier is a type of transistor amplifier configuration where the base terminal is common to both the input and output circuits.

2. **Identifying the Currents**:
...