EMF Units Match Energy per Charge

Steps:

• Define emf as the electrical potential difference, with units of joules per coulomb (J/C) or volts (V).
• Analyze option A: charge per energy is coulombs per joule (C/J), inverse of voltage units.
• Analyze option B: charge per time is coulombs per second (C/s), units of current (amperes, A).
• Analyze option C: energy per charge is joules per coulomb (J/C), matching emf units.
• Analyze option D: energy per time is joules per second (J/s), units of power (watts, W).

Why C is correct:

• Emf is defined by ε = W/q, where W is energy transferred and q is charge, so units are energy per unit charge (J/C).

Why the others are wrong:

• A: Represents inverse of emf units (C/J), not matching voltage.
• B: Describes electric current (A), unrelated to potential difference.
• D: Describes power (W), not potential.

Final answer: C