AP Physics C: Electricity and Magnetism Practice Test (2027)

How much work is required by an external force to bring a point charge +q from infinity to a distance r from a stationary point charge +Q?

A diagram shows two large, parallel conducting plates. The top plate is charged positively (+Q) and the bottom plate is charged negatively (-Q). The plates are separated by a distance 'd'. A small positive test charge is placed exactly halfway between the plates, far from the edges.

In what direction will the small positive test charge accelerate?

Which of the following statements is true regarding equipotential lines and electric field lines?

Two point charges, +q and -q, are placed at (a, 0) and (-a, 0) respectively. What is the electric potential at the origin (0,0)?

A positive charge +q is moved by an external force from point A to point B. If the electric potential at A is V_A and at B is V_B, and V_B > V_A, what is the work done BY the electric field during this process?

A graph with the horizontal axis representing distance 'r' from the center of a charged object and the vertical axis representing the magnitude of the electric field 'E'. The graph shows E increasing linearly from r=0 up to r=R, and then decreasing as 1/r^2 for r > R.

Which of the following charged objects would produce an electric field whose magnitude as a function of distance 'r' from its center is best represented by the given graph?

A thin non-conducting ring of radius R carries a total positive charge Q distributed uniformly around its circumference. Point P lies on the axis of the ring a distance x from its center. Which expression correctly gives the magnitude of the electric field at P?

A diagram shows electric field lines originating from a charge Q1 and terminating on a charge Q2. There are twice as many field lines originating from Q1 as there are terminating on Q2. The field lines point away from Q1 and towards Q2.

Based on the diagram of electric field lines, which of the following statements is true about charges Q1 and Q2?

An electron is moved from point A to point B in a uniform electric field. If the electric potential at point A (V_A) is higher than the electric potential at point B (V_B), what happens to the electric potential energy of the electron as it moves from A to B?

A point charge +Q is located at the origin. Which of the following statements correctly describes the electric field produced by this charge at a point P located at (x, 0) where x > 0?

A solid, uncharged conductor is placed in a uniform external electric field. Which of the following statements is true regarding the electric field inside the conductor once electrostatic equilibrium is reached?

In an undergraduate lab, a student places a single point charge of magnitude +Q = +4.0 nC at the exact center of a spherical Gaussian surface of radius r₁ = 0.25 m. She records the total electric flux through the surface as Φ₁ = 452 N·m²/C. For a second trial she keeps the charge and its position unchanged, but she mathematically re-draws the Gaussian surface as a concentric sphere of radius r₂ = 0.50 m (exactly double r₁). No other charges are added or removed, and no dielectric materials are introduced. She then computes the new flux Φ₂ through the enlarged Gaussian sphere.

Based on the scenario described, how does Φ₂ compare to Φ₁?

A thin non-conducting rod of length L carries total positive charge Q spread uniformly along its length. Point P lies on the axis of the rod (along the line containing the rod), a distance d beyond one end. Taking V = 0 at infinity, which expression gives the electric potential at P?

Electric potential at a point in an electric field is defined as:

A non-conducting solid sphere of radius R has a charge density that varies with distance from the center, given by ρ(r) = Ar, where A is a positive constant and r is the distance from the center. Assume the sphere is centered at the origin.

Using Gauss's Law, determine the magnitude of the electric field at a distance r < R from the center of the sphere.

Which of the following is a fundamental property of electric charge?

Two point charges, +q and -2q, are separated by a distance r. Which of the following statements correctly describes the electrostatic force exerted by the +q charge on the -2q charge?

In a tabletop electrostatics demonstration, three small charged pith balls are fixed at the vertices of an equilateral triangle whose sides each measure s = 0.12 m. The balls at the two bottom vertices each carry a charge of +Q = +2.0 nC. The ball at the top vertex carries a charge of −Q = −2.0 nC. Air resistance and gravity are negligible for the purpose of computing the electric field. A tiny movable test probe is then placed at the geometric centroid of the triangle, which is equidistant from all three vertices. The instructor asks the class to predict the direction of the net electric-field vector produced by the three source charges at the centroid.

Based on the configuration described, the net electric field at the geometric center of the triangle points in which direction?

A graph shows the x-component of the electric field, E_x, as a function of position x. From x=0 to x=a, E_x is a constant positive value E₀. From x=a to x=b, E_x is zero. From x=b to x=c, E_x is a constant negative value -E₀. Assume V(0) = 0.

Based on the given E_x vs x graph, which statement is true about the electric potential V(x) in this region, assuming V(0)=0?

Two point charges, q₁ = +4.0 µC and q₂ = −2.0 µC, are held 0.20 m apart in vacuum. Using k = 9.0 × 10⁹ N·m²/C², what is the magnitude of the electrostatic force each charge exerts on the other?