College Physics III – Thermodynamics, Electricity, and Magnetism
Definition
A volt (V) is the derived unit for electric potential, electric potential difference, and electromotive force in the International System of Units (SI). One volt is defined as the potential difference that will move one coulomb of charge with an energy of one joule.
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One volt is equivalent to one joule per coulomb ($1\ V = 1\ J/C$).
Voltmeters are instruments used to measure the electric potential difference between two points.
The concept of voltage is fundamental in understanding electric circuits and Ohm's Law, which states $V = IR$ where $I$ is current and $R$ is resistance.
In electrostatics, the electric potential at a point is often calculated using $V = k_e \frac{Q}{r}$ where $k_e$ is Coulomb's constant, $Q$ is charge, and $r$ is distance.
Voltage can be positive or negative depending on the relative potentials of the points being measured.
Review Questions
What does one volt represent in terms of energy and electric charge?
How do you calculate the electric potential at a point due to a single charge?
What instrument would you use to measure the electric potential difference between two points in a circuit?
Related terms
Electric Potential: The work needed per unit charge to move a test charge from a reference point to a specific point inside the field without producing any acceleration.
Electric Potential Difference: The work done to move a unit charge from one point to another. Also known as voltage.
Ohm's Law: $V = IR$, where $V$ represents voltage, $I$ represents current, and $R$ represents resistance.