Name a device that helps to maintain a potential difference across a conductor.

Explanation

To answer the question, "Name a device that helps to maintain a potential difference across a conductor," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Concept of Potential Difference**:
- Potential difference (voltage) is the difference in electric potential between two points in a circuit. It is necessary for current to flow through a conductor.

2. **Identifying the Device**:
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