Practice Test 5 - AP Physics C Electricity and Magnetism

20 questions. Answer them in any order, then submit to see your score and every explanation.

An LC circuit oscillates with a natural frequency $f$ . If the inductance is doubled and the capacitance is increased to eight times its original value, what is the new frequency of oscillation?
A very large, flat conducting plate has a uniform surface charge density $+\sigma$ on one of its faces. The plate is in electrostatic equilibrium. What is the magnitude of the electric field at a point just outside the surface of the plate?
A household night-light is modeled as a single resistor of $R=240\,\Omega$ connected directly across a $120\,\text{V}$ outlet. The circuit is steady-state and the resistor is the only load. Use $P=\frac{V^2}{R}$ to find the electrical power converted to thermal energy and light. Report the result in watts (W). Determine the power consumed by the appliance.
Two bar magnets are held near each other. A repulsive force is observed between them. This observation implies that:
What is the final charge on sphere C?
A conducting ring is dropped from rest so that it falls through a finite region of uniform magnetic field directed perpendicular to its plane. The force of gravity acts on the ring. Which statement best describes the ring's downward acceleration?
The magnetic field perpendicular to the plane of a $4.0$ cm by $4.0$ cm square loop of wire is given by $B(t) = 3.0t - 1.5t^2$ , where $B$ is in tesla and $t$ is in seconds. What is the magnitude of the magnetic flux through the loop at $t=2.0$ s?
An ideal transformer has $N_p=200$ and $N_s=800$ with $V_p=9.0\,\mathrm{V}$ ; calculate induced secondary voltage magnitude.
Maxwell's modification to Ampère's law includes which additional term to account for changing electric fields?
A uniform electric field $\vec{E} = E_0 \hat{k}$ exists in space. What is the electric flux through the curved surface of a hemisphere of radius R whose circular base lies in the xy-plane, centered at the origin, with its dome in the $z>0$ region?
The current $I$ flowing through a resistor $R$ is given as a function of time $t$ by the expression $I(t) = I_0 e^{-t/\tau}$ , where $I_0$ and $\tau$ are positive constants. What is the instantaneous power $P(t)$ being dissipated by the resistor?
Three wires carry time-dependent currents $I_1(t)$ , $I_2(t)$ , and $I_3(t)$ into a single junction. The currents are periodic with period $T$ . The time-average value of a current $I(t)$ is defined as $\langle I \rangle = \frac{1}{T}\int_0^T I(t) dt$ . If $\langle I_1 \rangle = +3 \text{ A}$ and $\langle I_3 \rangle = -5 \text{ A}$ , what is the time-average value of the current $I_2$ ?
A flat circular surface of radius $r$ is placed in a uniform electric field of magnitude $E$ . The field is directed perpendicular to the plane of the surface. What is the electric flux through the surface?
A student wishes to use Gauss's law to determine the electric field produced by a charge distribution. Which of the following is a necessary property of the Gaussian surface they choose?
For a steady conventional current to exist in a circuit, which of the following conditions must be met?
Gauss's law is theoretically valid for any closed surface and any charge distribution. However, it is only practically useful for calculating the electric field when...
The process of 'grounding' a conductor is best described as connecting it to an object that can act as a nearly infinite source or sink of electrons, thereby...
A closed surface is in a region where the electric field is non-uniform. The net electric flux through the surface is found to be zero. Which of the following statements must be true?
How does the potential difference across the resistor, $V_R$ , change with time?
A sample of paramagnetic material, such as aluminum, is placed in a non-uniform magnetic field. The sample will experience a net force that is:

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