Q: A circuit contains a $$10\,\Omega$$ resistor and a $$5\,\Omega$$ resistor in series. What is the total resistance?

$$R_{\text{total}} = 15\,\Omega$$

Q: A $$2\,\mu\text{F}$$ capacitor and a $$4\,\mu\text{F}$$ capacitor are connected in parallel. What is the equivalent capacitance?

$$C_{\text{eq}} = 6\,\mu\text{F}$$

Question 1

A point charge $$q is $$placed at the origin. What is the electric field at a distance $$r$$ from the charge in vacuum?

Accepted Answer

$$E = \frac{q}{4\pi\$$epsilon_0$$ r^2$}$$

Question 2

Which of the following best describes Gauss’s Law?

Accepted Answer

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

Question 3

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

Accepted Answer

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

Question 4

A $$12\,	ext{V}$$ battery is connected to a resistor of $$4\,\Omega. $$What is the current through the resistor?

Accepted Answer

$$I = 3\,	ext{A}$$

Question 5

Which of the following statements about electric potential is correct?

Accepted Answer

Electric potential is a scalar quantity and can be negative.

Question 6

A wire of length $$L$$ and cross-sectional area $$A$$ has resistivity $$\rho. $$What is its resistance?

Accepted Answer

$$R = \frac{\rho L}{A}$$

Question 7

A circuit contains a $$10\,\Omega$$ resistor and a $$5\,\Omega$$ resistor in series. What is the total resistance?

Accepted Answer

$$R_{	ext{total}} = 15\,\Omega$$

Question 8

A $$2\,\mu	ext{F}$$ capacitor and a $$4\,\mu	ext{F}$$ capacitor are connected in parallel. What is the equivalent capacitance?

Accepted Answer

$$C_{	ext{eq}} = 6\,\mu	ext{F}$$

Question 9

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

Accepted Answer

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

Question 10

A charged particle with charge $$q$$ and velocity $$\vec{v}$$ moves in a magnetic field $$\vec{B}. $$What is the magnitude of the magnetic force?

Accepted Answer

$$F = q v B \sin	heta$$

Question 11

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

Accepted Answer

The induced emf in a closed loop equals the negative rate of change of magnetic flux through the loop.

Question 12

A coil with $$N$$ turns and area $$A is $$placed in a changing magnetic field. If the magnetic field changes from $$B_1 to$$ $$B_2 in $$time $$\Delta t$$, what is the average induced emf?

Accepted Answer

$$\mathcal{E} = -N \frac{(B_2$ - B_1$)A}{\Delta t}$$

Question 13

A circuit contains a battery, a resistor, and a capacitor in series. What happens to the voltage across the capacitor as time increases?

Accepted Answer

It increases and approaches the battery voltage.

Question 14

A patient receives an MRI scan, which uses strong magnetic fields. Which law explains the induced currents in the patient’s tissues?

Accepted Answer

Faraday’s Law

Question 15

A $$60\,	ext{W}$$ light bulb is connected to a $$120\,	ext{V}$$ outlet. What is the current through the bulb?

Accepted Answer

$$I = 0.5\,	ext{A}$$

Question 16

Which of the following is NOT a correct application of Kirchhoff’s Rules?

Accepted Answer

The sum of the resistances in a loop equals the sum of the voltages.

Question 17

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

Accepted Answer

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

Question 18

A $$10\,\Omega$$ resistor and a $$20\,\Omega$$ resistor are connected in parallel. What is the equivalent resistance?

Accepted Answer

$$R_{	ext{eq}} = \frac{10 	imes 20}{10 + 20} = 6.67\,\Omega$$

Question 19

A $$50\,	ext{Hz} AC $$circuit contains a $$100\,\Omega$$ resistor and a $$0.1\,	ext{H}$$ inductor. What is the inductive reactance?

Accepted Answer

$$X_L = 2\pi f L = 2\pi 	imes 50 	imes 0.1 = 31.4\,\Omega$$

Electricity and Magnetism: PHYS 220B Syllabus and Course Structure

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