AP Physics C: Electricity and Magnetism Flashcards: Electric Potential
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 16 cards to help you master important concepts.
What is the general relationship between electric potential and the electric field?
The electric field is equal to the negative of the spatial rate of change of the electric potential, and its vectors point from higher potential to lower potential.
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What is the general relationship between electric potential and the electric field?
The electric field is equal to the negative of the spatial rate of change of the electric potential, and its vectors point from higher potential to lower potential.
What does the negative sign in the equation E_x = -dV/dx signify?
The negative sign indicates that the electric field points in the direction of the steepest decrease in electric potential.
What is the integral expression used to find the electric potential (V) of a continuous charge distribution?
The expression is V = (1 / 4πε₀) ∫(dq / r), which integrates the potential contribution from each infinitesimal charge element dq over the entire distribution.
What are equipotential lines and what do they represent?
Equipotential lines are a tool to describe a field; they connect points of equal electric potential, and can be used to predict the motion of charged objects.
What principle allows you to calculate the total electric potential from a configuration of multiple charged objects?
The principle of superposition is used, which states that the total potential is the algebraic sum of the potentials from each individual charge.
A positive test charge is moved along an equipotential line. How much work is done by the electric field?
Since the potential difference (ΔV) is zero along an equipotential line, the change in potential energy is zero, and therefore zero work is done by the electric field.
How is the electric potential due to a configuration of charged objects described or calculated?
The potential is described by the sum of the potentials from each object, which can be found using integration for continuous distributions and the principle of superposition.
What is electric potential?
Electric potential describes the electric potential energy per unit charge at a specific point in space.
What is the equation that relates electric potential difference (ΔV) to the change in electric potential energy (ΔU_E)?
The relationship is given by the equation ΔV = ΔU_E / q, where q is the charge being moved.
Define electric potential difference (ΔV).
The electric potential difference is the change in electric potential energy per unit charge when a test charge is moved between two points.
What is the purpose of using electric field vector maps and equipotential lines?
These tools are used to visualize and describe the electric field produced by a charge configuration and to predict how charged objects will move within that field.
Explain the meaning of the negative sign in the potential difference equation ΔV = -∫E·dr.
The negative sign signifies that moving in the direction of the electric field results in a decrease in electric potential.
How do electric field vectors relate geometrically to equipotential lines?
Electric field vectors are always perpendicular to equipotential lines and point in the direction of decreasing potential.
If the electric potential is constant throughout a region of space, what must be true about the electric field in that region?
If the potential V is constant, its spatial derivative (dV/dx) is zero, which means the electric field E must be zero throughout that region.
How can you determine a component of the electric field, like E_x, from the electric potential V?
A component of the electric field is the negative of the derivative of the potential with respect to that direction, as shown by the equation E_x = -dV/dx.
If you are given the electric field (E) along a path, how do you calculate the potential difference (ΔV) between the path's start and end points?
The potential difference is found by calculating the negative of the integral of the dot product of the electric field and displacement, using the equation ΔV = -∫E·dr.