Question 1

A point charge $$q is $$placed at the center of a spherical conducting shell of radius $$R. $$What is the electric field at a distance $$r$$ from the center, where $$r \u003c R$$?

Accepted Answer

The electric field is $$E = \frac{q}{4\pi\$$epsilon_0$$ r^2$}.$$

Question 2

Which of the following best describes Gauss’s Law?

Accepted Answer

The total electric flux through a closed surface is equal to the total charge enclosed divided by $$\$$epsilon_0$$.

Question 3

A parallel plate capacitor with plates of area $$A$$ and separation $$d is $$filled with a dielectric of dielectric constant $$\kappa. $$What is the capacitance?

Accepted Answer

$$C = \frac{\kappa \$$epsilon_0$$ A}{d}$$

Question 4

A resistor ($$R$$), capacitor ($$C$$), and battery ($$V_0) $$are connected in series. What is the charge on the capacitor at time $$t$$ after the circuit is closed?

Accepted Answer

$$Q(t) = C V_0$ \left(1 - e$$^{-t/(RC)}$$\right)$$

Question 5

A wire carries a current $$I$$ and is placed in a uniform magnetic field $$\vec{B}$$ perpendicular to the wire. What is the force per unit length on the wire?

Accepted Answer

$$F/L = I B$$

Question 6

Which equation represents Faraday’s Law of electromagnetic induction?

Accepted Answer

$$\mathcal{E} = -\frac{d\Phi_B}{dt}$$

Question 7

A long straight wire carries a current $$I. $$What is the magnetic field at a distance $$r$$ from the wire according to Ampère’s Law?

Accepted Answer

$$B = \frac{\mu_0$ I}{2\pi r}$$

Question 8

A charged particle with charge $$q$$ and mass $$m$$ enters a region with a uniform magnetic field $$B$$ perpendicular to its velocity. What is the radius of its circular path?

Accepted Answer

$$r = \frac{m v}{q B}$$

Question 9

Which of the following statements about Maxwell’s equations is correct?

Accepted Answer

They unify electricity and magnetism into a single theory of electromagnetism.

Question 10

A transformer has a primary coil with $$N_1$$ turns and a secondary coil with $$N_2$$ turns. If the input voltage is $$V_1$$, what is the output voltage $$V_2$$?

Accepted Answer

$$V_2$$ = $$V_1$$ \frac{$$N_2$$}{$$N_1$$}$$

Question 11

A circuit contains a resistor ($$R$$), inductor ($$L$$), and capacitor ($$C) in $$series with an AC voltage source. What is the impedance $$Z of $$the circuit?

Accepted Answer

$$Z = \sqrt{R^2$ + \left(\omega L - \frac{1}{\omega C}\$$right)^2$$}$$

Question 12

A capacitor is charged to voltage $$V_0$$ and then discharged through a resistor $$R. $$What is the voltage across the capacitor at time $$t$$?

Accepted Answer

$$V(t) = V_0$ e$$^{-t/(RC)}$$

Question 13

Which of the following is a consequence of Lenz’s Law?

Accepted Answer

The induced current opposes the change in magnetic flux.

Question 14

A solenoid of length $$l$$ and $$N$$ turns carries a current $$I. $$What is the magnetic field inside the solenoid?

Accepted Answer

$$B = \frac{\mu_0$ N I}{l}$$

Question 15

A charged particle moves in a region where both electric field $$\vec{E}$$ and magnetic field $$\vec{B}$$ are present. What is the force on the particle?

Accepted Answer

$$\vec{F} = q(\vec{E} + \vec{v} 	imes \vec{B})$$

Question 16

Which of the following best describes the behavior of an ideal conductor in electrostatics?

Accepted Answer

The electric field inside the conductor is zero.

Question 17

A capacitor and inductor are connected in series. If the initial charge on the capacitor is $$Q_0$$, what is the maximum current in the circuit?

Accepted Answer

$$I_{max} = \frac{Q_0$}{\sqrt{LC}}$$

Question 18

Which of the following is NOT a direct consequence of Maxwell’s equations?

Accepted Answer

The quantization of electric charge.

Question 19

A hospital uses a transformer to step down voltage from 2400 V to 120 V for medical equipment. If the primary coil has 2000 turns, how many turns should the secondary coil have?

Accepted Answer

100 turns

Physics C: Electricity and Magnetism – Course Syllabus and Lecture Outline Study Guide

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