Q: A long straight wire carries a current of $$5\ \mathrm{A}. $$What is the magnitude of the magnetic field at a distance $$0.1\ \mathrm{m}$$ from the wire? (Use $$\mu_0$ = 4\pi \times 10$$^{-7}$$\ \mathrm{T\cdot m/A})$$

$$B = 1 \times 10$$^{-5}$$\ \mathrm{T}$$

Q: A patient undergoes an MRI scan, which uses a strong uniform magnetic field. If a proton in the patient's body moves perpendicular to a $$3\ \mathrm{T}$$ magnetic field with a speed of $$2 \times 10^6$\ \mathrm{m/s}$$, what is the magnitude of the magnetic force on the proton? (Charge of proton $$= 1.6 \times 10$$^{-19}$$\ \mathrm{C})$$

$$9.6 \times 10$$^{-13}$$\ \mathrm{N}$$

Q: A $$10\ \mu\mathrm{F}$$ capacitor is charged to $$100\ \mathrm{V}$$ and then connected across a $$2\ \Omega$$ resistor. How long will it take for the voltage across the capacitor to drop to $$50\ \mathrm{V}$$?

$$t = 1.39 \times 10$$^{-4}$$\ \mathrm{s}$$

Q: A $$5\ \mu\mathrm{C}$$ point charge is placed $$0.2\ \mathrm{m}$$ from a point in space. What is the magnitude of the electric field at that point? ($$\$$varepsilon_0$$ = 8.85 \times 10$$^{-12}$$\ \mathrm{C^2$/N\cdot m^2$})$$

$$E = 1.1 \times 10$$^{6}$$\ \mathrm{N/C}$$

Q: A hospital uses a defibrillator that stores $$400\ \mathrm{J} of $$energy in a $$100\ \mu\mathrm{F}$$ capacitor. What is the voltage across the capacitor?

$$V = 2.83 \times 10$$^{3}$$\ \mathrm{V}$$

Question 1

A mass-spring system oscillates with a period $$T$$ and amplitude $$A. If $$the mass is doubled and the amplitude is halved, what happens to the period of oscillation?

Accepted Answer

The period increases by a factor of $$\sqrt{2}.$$

Question 2

A string fixed at both ends supports a standing wave with three antinodes. If the length of the string is $$L$$ and the wave speed is $$v$$, what is the frequency of this standing wave?

Accepted Answer

$$f = \dfrac{3v}{2L}$$

Question 3

A sound wave travels through air at $$340\ \mathrm{m/s}. If $$its frequency is $$1700\ \mathrm{Hz}$$, what is its wavelength?

Accepted Answer

$$\lambda = 0.2\ \mathrm{m}$$

Question 4

A point charge $$q is $$placed at the center of a spherical conducting shell. According to Gauss' law, what is the electric flux through the shell?

Accepted Answer

$$\Phi_E = \dfrac{q}{\$$varepsilon_0$$}$$

Question 5

Which of the following best describes the effect of inserting a dielectric material with dielectric constant $$\kappa$$ between the plates of a parallel-plate capacitor, while keeping the charge constant?

Accepted Answer

The potential difference decreases by a factor of $$\kappa.$$

Question 6

A resistor of $$10\ \Omega$$ and a capacitor of $$100\ \mu\mathrm{F}$$ are connected in series to a $$12\ \mathrm{V}$$ battery. What is the time constant $$	au of $$the circuit?

Accepted Answer

$$	au = 1\ \mathrm{s}$$

Question 7

A wire carries a current $$I in $$the positive $$x-$$direction. According to the right-hand rule, what is the direction of the magnetic field directly above the wire?

Accepted Answer

Out of the page

Question 8

A $$2\ \mathrm{kg}$$ mass attached to a spring oscillates with a frequency of $$0.5\ \mathrm{Hz}. $$What is the spring constant $$k$$?

Accepted Answer

$$k = 20\ \mathrm{N/m}$$

Question 9

A $$12\ \mathrm{V}$$ battery is connected to three resistors in series: $$2\ \Omega$$, $$3\ \Omega$$, and $$5\ \Omega. $$What is the current in the circuit?

Accepted Answer

$$I = 1.2\ \mathrm{A}$$

Question 10

A long straight wire carries a current of $$5\ \mathrm{A}. $$What is the magnitude of the magnetic field at a distance $$0.1\ \mathrm{m}$$ from the wire? (Use $$\mu_0$ = 4\pi 	imes 10$$^{-7}$$\ \mathrm{T\cdot m/A})$$

Accepted Answer

$$B = 1 	imes 10$$^{-5}$$\ \mathrm{T}$$

Question 11

A parallel-plate capacitor is charged and then disconnected from the battery. If the plates are pulled apart to double their separation, what happens to the energy stored in the capacitor?

Accepted Answer

It doubles.

Question 12

A patient undergoes an MRI scan, which uses a strong uniform magnetic field. If a proton in the patient's body moves perpendicular to a $$3\ \mathrm{T}$$ magnetic field with a speed of $$2 	imes 10^6$\ \mathrm{m/s}$$, what is the magnitude of the magnetic force on the proton? (Charge of proton $$= 1.6 	imes 10$$^{-19}$$\ \mathrm{C})$$

Accepted Answer

$$9.6 	imes 10$$^{-13}$$\ \mathrm{N}$$

Question 13

A $$10\ \mu\mathrm{F}$$ capacitor is charged to $$100\ \mathrm{V}$$ and then connected across a $$2\ \Omega$$ resistor. How long will it take for the voltage across the capacitor to drop to $$50\ \mathrm{V}$$?

Accepted Answer

$$t = 1.39 	imes 10$$^{-4}$$\ \mathrm{s}$$

Question 14

A charged particle moves in a region where both electric and magnetic fields are present and perpendicular to each other. If the particle moves undeflected, what is the relationship between the fields and the particle's velocity?

Accepted Answer

$$v = \dfrac{E}{B}$$

Question 15

A transformer is used to step down the voltage from $$120\ \mathrm{V} to$$ $$12\ \mathrm{V}$$ for a device. If the primary coil has $$600$$ turns, how many turns must the secondary coil have?

Accepted Answer

$$60$$

Question 16

A $$1.5\ \mathrm{m}$$ long tube, open at both ends, resonates at its fundamental frequency. What is the wavelength of the sound wave?

Accepted Answer

$$3.0\ \mathrm{m}$$

Question 17

A $$5\ \mu\mathrm{C}$$ point charge is placed $$0.2\ \mathrm{m}$$ from a point in space. What is the magnitude of the electric field at that point? ($$\$$varepsilon_0$$ = 8.85 	imes 10$$^{-12}$$\ \mathrm{C^2$/N\cdot m^2$})$$

Accepted Answer

$$E = 1.1 	imes 10$$^{6}$$\ \mathrm{N/C}$$

Question 18

A hospital uses a defibrillator that stores $$400\ \mathrm{J} of $$energy in a $$100\ \mu\mathrm{F}$$ capacitor. What is the voltage across the capacitor?

Accepted Answer

$$V = 2.83 	imes 10$$^{3}$$\ \mathrm{V}$$

Question 19

A coil with $$200$$ turns and area $$0.01\ \mathrm{m}^2 is $$placed in a uniform magnetic field of $$0.5\ \mathrm{T}. If $$the field is reduced to zero in $$0.1\ \mathrm{s}$$, what is the average induced emf?

Accepted Answer

$$10\ \mathrm{V}$$

Physics 2051: General Physics II – Oscillations, Waves, and Electromagnetism (Syllabus and Study Guide)

Study Guide - Practice Questions

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