A potential difference of one volt indicates energy transfer of how much per coulomb?

A potential difference of one volt indicates energy transfer of how much per coulomb?

• A. 1 joule per volt
• B. 1 watt per coulomb
• C. 1 joule per ampere
• D. 1 joule per coulomb

Answer: (D)

Voltage tells you how much energy is given to or taken from a charge as it moves through a potential difference. It is energy per unit charge. So if the potential difference is one volt, that means each coulomb of charge moves through the field and gains or loses one joule of energy. In the relation E = qV, with q = 1 coulomb and V = 1 volt, you get E = 1 joule. Therefore, energy transfer per coulomb is 1 joule per coulomb. The other options mix different quantities: a watt per coulomb would be energy per time per charge (not energy per charge), and a joule per ampere would be energy per unit current (also not energy per charge). So they don’t describe energy per charge the way voltage does.

Voltage tells you how much energy is given to or taken from a charge as it moves through a potential difference. It is energy per unit charge. So if the potential difference is one volt, that means each coulomb of charge moves through the field and gains or loses one joule of energy. In the relation E = qV, with q = 1 coulomb and V = 1 volt, you get E = 1 joule. Therefore, energy transfer per coulomb is 1 joule per coulomb.

The other options mix different quantities: a watt per coulomb would be energy per time per charge (not energy per charge), and a joule per ampere would be energy per unit current (also not energy per charge). So they don’t describe energy per charge the way voltage does.