Question

When a copper wire is connected to a battery the electric field in the wire is

• A. more at positive terminal
• B. more at negative terminal
• C. not uniform in the wire
• D. uniform in the wire

Answer 1

The Correct Option is D

To determine the electric field in a copper wire when it is connected to a battery, we need to analyze how the electric field behaves within the wire.

1. Understanding Electric Field in a Wire:
When a copper wire is connected to a battery, an electric field is established within the wire due to the potential difference between the positive and negative terminals of the battery.
The electric field drives the flow of electrons (current) through the wire from the negative terminal (higher potential) to the positive terminal (lower potential).

2. Uniformity of the Electric Field:
In an ideal conductor like a copper wire with uniform cross-sectional area and no external influences, the electric field inside the wire is uniform along its length.
This is because the electric field is directly related to the potential gradient ($E = -\frac{dV}{dx}$), and in a steady-state situation, the potential drop is linear across the wire. Hence, the electric field does not vary along the wire.

3. Behavior at Terminals:
At the positive terminal, the electric field points inward toward the wire, as this is where the electrons are being "pulled" into the battery.
At the negative terminal, the electric field points outward from the wire, as this is where the electrons are being "pushed" out of the battery.
However, these effects at the terminals do not affect the uniformity of the electric field within the wire itself.

4. Conclusion:
The electric field inside the wire is uniform because the potential drop is linear, and there are no variations in the wire's properties or external influences that would cause non-uniformity.

Final Answer:
The correct option is: ${(D) \text{ uniform in the wire}}$