Final Exam Quizlet - PHY 162

A 2 uF and a 1 uF capacitor are connected in series and a potential difference is applied across the combination. The 1 uF capacitor has: a. twice the potential difference of the 2 uF capacitor b. half the charge of the 2 uF capacitor c. none of the above d. twice the charge of the 2 uF capacitor e. half the potential difference of the 2 uF capacitor

a

A 200-N/C electric field is in the positive x direction. the force on an electron in this field is directed: a. in the negative x direction b. in the positive y direction c. in the positive x direction d. in the negative y direction

a

A closed cylinder with a 0.15 m radius ends is in a uniform electric field of 300 N/C, perpendicular to the ends. The total flux through the cylinder is: a. 0 N*m^2/C b. 21 N*m^2/C c. 4.2 N*m^2/C d. can't tell without knowing the length of the cylinder e. 280 N*m^2/C

a

A parallel plate capacitor C has a charge Q. The actual charges on its plates are: a. Q, -Q b. Q, 0 c. Q/2, Q/2 d. Q/2, -Q/2 e. Q, Q

a

Beats in sound occur when: a. two waves of slightly different frequency interfere b. waves travel in two media having slightly different sound velocities c. source and observer are in relative motion d. a reflected sound wave interferes with an incident wave e. two waves of the same freq. interfere

a

Comparing the field of a single point charge with the field of an electric dipole a. the field of the point charge decreases less rapidly with distance b. the fields decrease equally rapidly with distance c. the field of the point charge decreases more rapidly with distance d. the field of the point charge decreases more rapidly with distance by only along the dipole axis e. the field of the point charge decreases less rapidly with distance but only perpendicular to the dipole axis

a

Comparing the field of a single point charge with the field of an infinitely long line charge, a. the field of the point charge decreases more rapidly with distance b. the field of the point charge decreases less rapidly with distance c. the field decreases equally rapidly with distance

a

Faraday's law states that an induced emf is proportional to: a. the rate of change of the magnetic flux b. the rate of change of the electric flux c. the rate of change of the electric field d. zero e. the rate of change of the magnetic field

a

If I is the current density and dA is a vector element of area then the integral of J*dA over an area represents: a. the current through the area b. the average current density at the position of the area c. the resistance of the area d. the resistivity of the area e. the electric flux through the area

a

Suitable units for u0 are: a. tesla*meter/ampere b. kilogram*ampere/meter c. weber/meter d. tesla e. newton/ampere^2

a

The electric potential at a certain point is given by V=-7.5x^2 + 3x, where V is in volts and x is in meters. What is the electric field, in N/C at the point x=2m? a. E=27i b. E=15i c. E=-15i d. E=0 e. E=33i

a

The speed of a sinusoidal wave on a string depends on: a. the tension in the string b. the amplitude of the wave c. the wavelength of the wave d. the frequency of the wave e. the length of the string

a

Two long straight current carrying parallel wires cross the x axis and carry currents I (at x=2) and 3I (at x=6) in the same direction. At what value of x is the net magnetic field zero? a. 3 b. 1 c. 0 d. 7 e. 5

a

Two long straight wires enter a room through a window. One carries a current of 3 A into the room while the other carries a current of 5 A out. The magnitude of the path integral equals B*ds around the window frame is: a. 2.5E-6 T*m b. 1E-5 T*m c. 3.8E-6 T*m d. 6.3E-6 T*m e. none of these

a

Two parallel wires, 4 cm apart, carry currents of 2 A and 4 A respectively, in the same direction. The force per unit length of one wire on the other is: a. 4E-5 N/m, attractive b. r4-5 N/m, repulsive c. 1E-3 N/m, attractive d. none of these e. 1E-3 N/m, repulsive

a

Which of the following statements is not true for a conductor in electrostatic equilibrium? a. the surface charge density is highest at locations where the radius of curvature is large, e.g. where the surface is essentially flat b. the electric field just outside any point on the surface of a charge conductor is perpendicular to the surface of the conductor c. the electrostatic field is zero everywhere inside the conductor d. a net charge on an isolated conductor resides entirely on its surface

a

Two experimenters A and B measure an electric field produced by stationary charges. Experimenter A uses a test charge q(zero) and experimenter B uses a test charge 2q(zero). A finds a field that is: a. the same as the field found by B b. less than the field found by B c. either greater or less than the field found by B depending on the acceleration of the test charges d. either greater of less than the field found by B depending on the masses of the test charges e. greater than the field found by B

a.

A 45 m long wire is coiled so that it makes a coil containing 100 circular loops, one on top of the other. If the wire carried a current of 13 A, what is the magnetic dipole moment of the coil? a. 2.6 A*m^2 b. 21 A*m^2 c. 1.2 A*m^2 d. 6.7 A*m^2 e. 3.3 A*m^2

b

A magnet moves inside a coil. Consider the following factors: i. strength of the magnet ii. number of turns in the coil iii. speed at which the magnet moves Which can affect the emf induced in the coil? a. i and ii only b. i, ii, iii c. i only d. ii only e. iii only

b

An electric dipole consists of a particle with charge of +6E-6 C at the origin and a particle with a charge of -6E-6 C on the x axis at x=3E-3m. Its dipole moment is: a. 1.8E-8 Cm, in the -y direction b. 1.8E-8Cm, in the -x direction c. 1.8E-8 Cm, in the +x direction d. 0 Cm, because the net charge is 0 e. 1.8E-8 Cm, in the +y direction

b

Conduction electrons move to the left in a certain wire. This indicates that: a. the current density points left and the electric field points right b. the current density and electric field both point right c. the current density points left but the direction of the electric field is unknown d. the current density and electric fields both point left e. the current density points right and the electric field points left

b

Consider an electron is moving north in a region where the magnetic field is south. The magnetic force exerted on the electron is: a. north b. zero c. west d. up e. south

b

If the speed of sound is 343 m/s, the two lowest frequencies of an 0.5 m organ pipe, closed at one end, are approx.: a. 57 and 170 Hz b. 170 and 510 Hz c. 170 and 340 Hz d. 340 and 1020 Hz e. 240 and 680 Hz

b

In an overhead straight wire, the current is north. The magnetic field due to this current, at our point of observation, is: a. north b. west c. east d. up e. down

b

In the formula F=qv*B (cross product): a. all three vectors must be mutually perpendicular b. F must be perpendicular to both v and B c. F must be perpendicular to v but not necessarily to B d. F must be perpendicular to B but not necessarily to v e. v must be perpendicular to B but not necessarily to F

b

Lines of the magnetic field produced by a long straight wire carrying a current are: a. opposite to the direction of the current b. circles concentric with the wire c. lines similar to those produced by a bar magnet d. in the direction of the current e. leave the wire radially

b

Pulling the plates of an isolated (i.e. not connected to battery) charged capacitor apart: a. does not affect the capacitance b. increases the potential difference c. does not affect the potential difference d. increases the capacitance e. decreases the potential difference

b

The magnetic field B inside a long ideal solenoid is independent of: a. the current b. the cross sectional area c. the spacing of the windings d. the number of turns of the wire e. the direction of the current

b

The plate areas and plate separations of five parallel plate capacitors are: 1. area A, separation d 2. area 2A, separation 2d 3. area 2A, separation d/2 4. area A/2, separation 2d 5. area A, separation d/2 Rank these according to the capacitances, greatest to least. a. 5, 3=4, 1, 2 b. 3, 5, 1=2, 4 c. 1, 2, 3, 4, 5 d/ 4, 1=2, 5, 3 e. 5, 4, 3, 2, 1

b

Two identical capacitors are connected in series and two, each identical to the first, are connected in parallel. The equivalent capacitance of the series connection is ____ the equivalent capacitance of parallel connection. a. half b. one fourth c. four times d. twice e. the same as

b

Two straight wires pierce the plane of the paper at vertices of an equilateral triangle, with side lengths of 4 cm. They each carry 2 A, out of the paper. The magnetic at the third vertex (P) has magnitude: a. 1E-5 T b. 1.7E-5 T c. 8.7E-6 T d. 2E-5 T e. 5E-6 T

b

Two waves are traveling on two different strings. The displacement of one is given by y1(x,t)=(Ym)sin(kx+(omega)t) and of the other by y2(x,t)=(Ym)sin(kx+(omega)t+(phi)). What is the difference between the two waves? a. the displacement of wave y1 is always greater than the displacement of y2 b. the two waves are identical except for their displacement at t=0 c. wave y1 has a shorter wavelength than wave y2 d. wave y1 has a higher freq than wave y2 e. wave y1 has a smaller amplitude than wave y2

b

What is the difference between transverse and longitudinal waves? a. only longitudinal waves transmit matter b. in transverse waves the displacement is perpendicular to the direction of propagation on of the wave, while in longitudinal waves the displacement is parallel to the direction of propagation c. mechanical waves are transverse waves while electromagnetic waves are longitudinal d. plane waves are transverse waves while spherical waves are longitudinal e. only transverse waves transmit energy

b

fully destructive interference between two sinusoidal waves of the same freq and amplitude occurs only if they: a. travel in the same direction and are 90 degrees out of phase b. travel in the same direction and are 180 degrees out of phase c. travel in the same direction and are in phase d. travel in the same direction and are 45 degrees out of phase e. travel in the same direction and are 270 degrees out of phase

b

A copped hoop is help in a vertical east west plane in a uniform magnetic field whose field lines run along the north south direction. The largest induced emf is produced when the hoop is: a. rotated around a north south axis b. moved rapidly, without rotation, toward the south c. rotated about an east west axis d. moved rapidly, without rotation, towards the northwest e. moved rapidly, without rotation, toward the east

c

A disk of uniform positive surface charge density lies in the x-y plane, centered on the origin. Along the positive z axis, the direction of the electric field is: a. there is no electric field along the positive z axis b. in the negative z direction c. in the positive z direction d. in the positive y direction e. in the positive x direction

c

A long straight wire carrying a 3 A current enters a room through a window 1.5 m high and 1.0 m wide. The path integral equals B*ds around the window frame has the value: a. 0.2 T*m b. 2.5E-7 T*m c. 3.8E-6 T*m d. 3E-7 T*m e. none of these

c

A wave is described by y(x,t) = 0.1 sin (3x-10t), where x is in meters, y is in cm, and t is in seconds. The angular frequency is: a. 10pi rad/s b. 3.0 rad/s c. 10 rad/s d. 0.1 rad/s e. 20pi rad/s

c

An electron travels due north through a vacuum in a region of uniform magnetic field B that is also directed due north. It will: a. following a right handed corkscrew path b. speed up c. be unaffected by the field d. follow a left handed corkscrew path e. slow down

c

Conductivity is: a. the same as resistivity, it is just more convenient to use for good conductors b. not a meaningful quantity for an insulator c. reciprocal of resistivity d. expressed in 1/ohm e. equal to 1/resistance

c

If the magnetic flux through a certain region is changing with time: a. energy must be dissipated as heat b. a magnetic field must exist at the boundary c. an emf must exist around the boundary d. a current must flow around the boundary e. an electric field must not exist at the boundary

c

The displacement of a string carrying a traveling sinusoidal wave is given by y(x,t) = (Ym)sin(kx-(omega)t-(phi). At time t=0 the point at x=0 has a displacement of 0 and is moving in the postive y direction. The phase constant phi is: a. 180 degrees b. 90 degrees c. 0 degrees d. 135 degrees e. 270 degrees

c

The magnetic field a distance 2 cm from a long straight current carrying wire is 2E-5 T. The current in the wire is: a. 0.16 A b. 1.0 A c. 2.0 A d. 25 A e. 4.0 A

c

The magnetic field outside a long straight current carrying wire depends on the distance R from the wire axis according to: a. 1/R^2 b. 1/R^3 c. 1/R d. 1/R^(3/2) e. R

c

The magnetic flux through a surface: a. is the line integral of the magnetic field around the edge of the surface b. is the magnetic field multiplied by the area c. is the amount of magnetic field piercing the surface d. is the amount of magnetic field skimming along the surface e. does not depend on the area involved

c

When listening to tuning forks of frequency 256 Hz and 260 Hz, one hears the following number of beats per second: a. 2 b. 8 c. 4 d. 0 e. 258

c

Which of the following cylindrical wires has the largest resistance? All wires are made of the same material. a. a wire of length L and diameter 2d b. a wire of length L and diameter d c. a wire of length L and diameter d/2 d. a wire of length L/2 and diameter d e. a wire of length L/2 and diameter 2d

c

an isolated point charge produces an electric field with magnitude E at a point 2 m away. At a point 4 m away from the particle the magnitude of the field is: a. 2E b. 4E c. E/4 d. E/2 e. E

c

A long straight wire is in the plane of a rectangular conducting loop. The straight wire carried a constant current i. While the wire is being moved towards the loop, the current in the loop is: a. clockwise in the left side and counterclockwise in the right side b. counterclockwise in the left side and clockwise in the right side c. zero d. counterclockwise e. clockwise

d

A standing wave in a pipe has nodes that are 1.2 meters apart. What is the wavelength of the wave? a. 1.2 m b. cannot tell without knowing which harmonic it is c. 0.6 m d. 2.4 m e. 1.8m

d

A toroid with a square cross section carried current i. The magnetic field has its largest magnitude: a. at none of the above b. at the center of the hole c. just inside the toroid at its outer surface d. just inside the toroid at its inner surface e. at any point inside (the field is uniform)

d

An electric field exerts a torque on a dipole only if: a. the field is not perpendicular to the dipole moment b. the field is uniform c. the field is parallel to the dipole moment d. the field is not parallel to the dipole moment e. the field is perpendicular to the dipole moment

d

An organ pipe with one end open and the other closed is operating at one of its resonant frequencies. The open and closed ends are respectively: a. pressure antinode, pressure antinode b. pressure node, pressure node c. displacement antinode, pressure node d. pressure node, displacement node e. displacement node, displacement node

d

Current has units: a. ohm b. volt c. coulomb d. coulomb/second e. kilowatt-hour

d

J.J. Thomson's experiment, involving the motion of an electron beam in mutually perpendicular E and B fields, gave the value of: a. the charge of an electron b. Avogadro's number c. the mass of an electron d. the charge/mass ration for an electron e. the Earth's magnetic field

d

A 2 T uniform magnetic field makes an angle of 30 degrees with the z axis. The magnetic flux though a 3 m^2 portion of the xy plane is: a. 6 Wb b. 2 Wb c. 12 Wb d. 3 Wb e. 5.2 Wb

e

A long straight wire is in the plane of a rectangular conducting loop. The straight wire carried a constant current i. While the current i is being shut off, the current in the loop is: a. counterclockwise in the left side and clockwise in the right side b. clockwise in the left side and counterclockwise in the right side c. counterclockwise d. zero e. clockwise

e

A magnetic field exerts a force on a charged particle: a. if the particle is at rest b. if the particle is moving along the field lines c. never d. always e. if the particle is moving across the field lines

e

A solenoid is 3 cm long and has a radius of 0.5 cm. It is wrapped with 500 turns of wire carrying a current of 2 A. The magnetic field at the center of the solenoid is: a. 1.3E-3 T b. 9.9E-8 T c. 16 T d. 20 T e. 4.2E-2 T

e

A uniform magnetic field makes an angle of 30 degrees with the z axis. If the magnetic flux through a 1 m^2 portion of the xy plane is 5 Wb then the magnetic flux through a 2 m^2 portion of the same plane is: a. 4.3 Wb b. 5 Wb c. 2.5 Wb d. 5.8 Wb e. 10 Wb

e

Charge Q is distributed uniformly throughout an insulating sphere of radius R. The magnitude of the electric field at a point R/2 from the center is: a. Q/(pi)(epsilon0)(R^2) b. 3Q/(4pi)(epsilon0)(R^2) c. Q/(4pi)(epsilon0)(r^2) d. none of these e. Q/(8pi)(epsilon0)(R^2)

e

Each plate of a capacitor stores a charge of magnitude 5mC when a 100-V potential difference is applied. The capacitance is: a. none of these b. 5 uF c. 10 uF d. 100 uF e. 50 uF

e

Electron are going around in a circle in a counterclockwise direction. At the center of the circle they produce a magnetic field that is: a. out of the page b. to the right c. zero d. to the left e. into the page

e

Fully constructive interference between two sinusoidal waves of the same frequency occurs only if they: a. travel in the same direction and are 90 degrees out of phase b. travel in the same direction and are 45 degrees out of phase c. travel in the same direction and are 270 degrees out of phase d. travel in the same direction and are 180 degrees out of phase e. travel in the same direction and are in phase

e

If I(zero)=10^-12 W/m^2, and I=4.5E-8 W/m^2, what is log (I/I(zero))? a. 3.7 b. 4.5E4 c. 18 d. 11 e. 4.7

e

If the sound level is increased by 10 db the intensity increases by a factor of: a. 20 b. 5 c. 100 d. 2 e. 10

e

If the sound level is increased by 20 db the intensity increases by a factor of: a. 2 b. 5 c. 10 d. 20 e. 100

e

Let Q denote charge, V denote the potential difference and U denote stored energy. Of these quantities, capacitors in parallel must have the same: a. Q only b. V and U only c. Q and U only d. U only e. V only

e

Solenoid 2 has twice the radius and six times the number of turns per unit length as solenoid 1. The ratio of the magnetic field in the interior of 2 to that in the interior of 1 is: a. 1/3 b. 4 c. 1 d. 2 e. 6

e

Two traveling waves, y1=Asin[k(x-vt)] and y2+Asin[k(x+vt)], are superposed on the same string. The distance between the adjacent nodes is: a. pi/2k b. 2pi/k c. vt/pi d. vt/2pi e. pi/k

e

What are the three main types of waves? a. transverse, longitudinal, linear b. plane, longitudinal, mechanical c. transverse, linear, water d. plane, spherical, transverse e. mechanical, electromagnetic, matter

e

Which of the following is the correct statement concerning electric field lines? a. field lines point away from negatively charge particles b. field lines may cross c. a point charge particle released from rest moves along a field line d. none of these are correct e. field lines are close together where the field is large

e

Which statement is correct? a. the sign of the flux through a closed surface depends on an arbitrary choice of sign for the surface vector b. the flux through a closed surface is always negative c. inward flux through a closed surface is positive and outward flux is negative d. the flux through a closed surface is always positive e. inward flux though a closed surface is negative and outward flux is positive

e

a wave is described by y(x,t) = 0.1 sin (3x+10t), where x is in meters, y is in cm, and t is in seconds. The angular wave number is: a. 0.1 rad/m b. 10pi rad/m c. 10 rad/m d. 3pi rad/m e. 3.0 rad/m

e