Potential Difference as Energy Transfer per Unit Charge

Steps:

• Define potential difference (V) as work done (W) per unit charge (Q), or V = W/Q.
• Recognize that in circuits, V represents electrical energy converted to other forms (e.g., heat, light) as charge flows through components.
• Identify the direction of energy transfer: from electrical potential energy to kinetic or thermal energy in loads.
• Match this to options, confirming A aligns with the conversion process.

Why A is correct:

• Potential difference quantifies the conversion of electrical energy to other forms (e.g., via V = IR in Ohm's law, where power P = IV dissipates as heat).

Why the others are wrong:

• B: Energy transfer for potential difference occurs across components like resistors, not inside the power supply, which generates the potential.
• C: This describes the power supply's role in converting chemical/mechanical energy to electrical, opposite to the drop across loads.
• D: While transfer happens in resistors, it's not exclusive; it occurs in any component where work is done on charge.

Final answer: A