Potential Difference Defined as Energy per Unit Charge

Steps:

• Recall the fundamental definition: potential difference is the work done per unit charge moved between two points.
• Eliminate A: power is energy per unit time, not per charge.
• Eliminate C: this describes Ohm's law (V = IR), a relationship, not the definition.
• Confirm B matches the core concept from physics principles.

Why B is correct:

• By definition, p.d. (V) = energy transferred (W) / charge (Q), so it's energy per unit charge.

Why the others are wrong:

• A: Power is energy per unit time (P = VI), not per charge.
• C: This is Ohm's law relating voltage, current, and resistance, not the definition of p.d.
• D: Unclear and incorrect; voltage times resistance gives IR * R, unrelated to p.d. definition.

Final answer: B