Question

The work done by an electric force in moving a unit positive charge from one point to another point in a circuit is called

• A. resistivity
• B. potential difference
• C. drift speed
• D. conductivity

Answer 1

The Correct Option is B

Step 1: Recall the definition of potential difference.

The **potential difference** between two points in a circuit is defined as the work done per unit charge in moving a charge from one point to the other. Mathematically, it is given by:

\[ \text{Potential Difference} = \frac{\text{Work Done}}{\text{Charge}}. \]

If the charge moved is \( 1 \, \text{C} \) (a unit positive charge), the work done directly gives the potential difference.

Step 2: Analyze the options.

• (1) Resistivity: Resistivity (\( \rho \)) is a property of a material that measures how strongly it opposes the flow of electric current. It is not related to the work done in moving a charge.
• (2) Potential difference: This is the correct term for the work done per unit charge in moving a charge from one point to another in a circuit.
• (3) Drift speed: Drift speed is the average velocity of charged particles (e.g., electrons) in a conductor under the influence of an electric field. It is not related to the work done in moving a charge.
• (4) Conductivity: Conductivity (\( \sigma \)) is the reciprocal of resistivity and measures how easily a material allows electric current to flow. It is not related to the work done in moving a charge.

Final Answer: The work done by an electric force in moving a unit positive charge from one point to another in a circuit is called \( \mathbf{\text{potential difference}} \), which corresponds to option \( \mathbf{(2)} \).