Question 1

Which of the following best describes Gauss’s Law?

Accepted Answer

The total electric flux through a closed surface is equal to the net charge enclosed divided by the permittivity of free space: $$\Phi_E = \frac{Q_{	ext{enc}}}{\$$varepsilon_0$$}$$

Question 2

A parallel-plate capacitor is connected to a battery and then disconnected. If the plates are pulled apart, what happens to the energy stored in the capacitor?

Accepted Answer

The energy increases because the capacitance decreases while the charge remains constant: $$U = \frac{Q^2$}{2C}$$

Question 3

Which of the following is a correct application of Kirchhoff’s Loop Rule?

Accepted Answer

The sum of the potential differences around any closed loop in a circuit must be zero: $$\sum \Delta V = 0$$

Question 4

A long straight wire carries a current $$I. $$What is the magnitude of the magnetic field at a distance $$r$$ from the wire?

Accepted Answer

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

Question 5

Which of the following statements about electromagnetic waves is correct?

Accepted Answer

They are transverse waves that propagate at the speed of light in a vacuum: $$c = 3.00 	imes 10^8$\ 	ext{m/s}$$

Question 6

A resistor and a capacitor are connected in series to a battery. What is the time constant $$	au$$ for the charging of the capacitor?

Accepted Answer

$$	au = RC$$

Question 7

Which of the following best describes the physical meaning of electric potential?

Accepted Answer

The electric potential at a point is the electric potential energy per unit charge at that point: $$V = \frac{U}{q}$$

Question 8

A charged particle moves perpendicular to a uniform magnetic field. What is the path of the particle?

Accepted Answer

It moves in a circle with radius $$r = \frac{mv}{qB}$$

Question 9

Which of the following is a correct statement of Faraday’s Law of Induction?

Accepted Answer

The induced emf in a closed loop equals the negative rate of change of magnetic flux through the loop: $$\mathcal{E} = -\frac{d\Phi_B}{dt}$$

Question 10

A light bulb is rated at 60 W when connected to a 120 V source. What is the resistance of the bulb?

Accepted Answer

$$R = \frac{V^2$}{P} = \frac{(120)^2$}{60} = 240\ \Omega$$

Question 11

Which of the following is a correct statement about the energy stored in an inductor?

Accepted Answer

The energy stored is $$U = \frac{1}{2} L I^2$

Question 12

A circuit contains a resistor, inductor, and capacitor in series (an LRC circuit). At resonance, which of the following is true?

Accepted Answer

The impedance is minimized and equals the resistance: $$Z = R$$

Question 13

Which of the following is a correct statement of Ampère’s Law?

Accepted Answer

The line integral of the magnetic field around a closed loop is proportional to the current enclosed: $$\oint \vec{B} \cdot d\vec{l} = \mu_0$ I_{	ext{enc}}$$

Question 14

A student connects three resistors of 2 $$\Omega$$, 4 $$\Omega$$, and 6 $$\Omega in $$parallel. What is the equivalent resistance?

Accepted Answer

$$R_{	ext{eq}} = \left( \frac{1}{2} + \frac{1}{4} + \frac{1}{6} \$$right)^{-1}$$ = 1\ \Omega$$

Question 15

Which of the following is a correct statement about the direction of the electric field produced by a positive point charge?

Accepted Answer

The electric field points radially outward from the charge.

Question 16

A wire loop is placed in a region where the magnetic field is increasing. What is the direction of the induced current?

Accepted Answer

The induced current flows in a direction that opposes the increase in magnetic flux (Lenz’s Law).

Question 17

Which of the following is a correct statement about the speed of light in different media?

Accepted Answer

The speed of light in a medium is $$v = \frac{c}{n}$$, where $$n is $$the index of refraction.

Question 18

A capacitor is connected to an AC source. Which of the following describes the capacitive reactance?

Accepted Answer

$$X_C = \frac{1}{\omega C}$$

Question 19

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

Accepted Answer

They unify electricity and magnetism and predict the existence of electromagnetic waves.

Physics 2212 Principles of Physics II: Course Syllabus and Structure

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