physics multiple choice

Four point charges Q of equal magnitude and sign are arranged on three of the corners of the square of side d as shown in the figure. Which one of the arrows shown represents the net force acting on the charge at the upper right hand corner of the square?

D (up and to the right)

Four waves are described by the following equations, where distances are measured in meters and times in seconds. I. y = 0.12 cos(3x - 21t) II. y = 0.15 sin(6x + 42t) III. y = 0.13 cos(6x + 21t) IV. y = -0.23 sin(3x - 42t) Which of these waves have the same period?

I. y = 0.12 cos(3x - 21t) and IV. y = -0.23 sin(3x - 42t)

a rectangular coil. with corners labeled ABCD, of length L and width w is places in a magnetic field B as shown in the figure. if there is a current I flowing through this coil, what is the force acting on section AB of this coil?

ILB

Consider an open pipe of length L. What are the wavelengths of the three lowest tones produced by this pipe?

L, 2L, 2L/3

which of the following equations represents a kirchhoff's voltage rule for the circuit shown in the figure

+6V - (12ohm)i1 = (8ohm)i2 + 4V =0V

three particles travel through a region of space where the magnetic field is out of the page, as shown in the figure. the charge of each of the three particles is, respectively

1 is negative, 2 is neutral, 3 is positive

a proton moving with a velocity of 4.0E4 m/s enters a magnetic field of 0.2T. if the proton travels in the direction of the magnetic field, what is the magnitude of the magnetic force on the proton

1.1 *10^-15 N

two identical small charged spheres are a certain distance apart, and each one initially experiences an electrostatic force of magnitude F due to the other. with time, charge gradually diminishes on both spheres by leaking off. when each of the spheres has lost half its initial charge, what will be the magnitude of the electrostatic force on each one

1/4 F

which of the following expressions is the correct representation for the speed of sound

1/sqrt EoUo

Two ideal parallel-plate capacitors are identical in every respect except that one has twice the plate area of the other. If the smaller capacitor has capacitance C, the larger one has capacitance

2C

You wish to double the speed of a wave in a string by tightening it. By what factor must you increase the tension in the string?

4

the electric potential at a distance of 4 m from a certain point charge is 200V relative to infinity. what is the potential at a distance of 2 m from the same charge

400 V

the figure shows two unequal charges +q and -Q. charge -Q has greater magnitude than charge +q. point X is midway between the charges. in what section of the line will there be a point where the resultant electric field is zero

VW

X and Y are two initially uncharged metal spheres on insulating stands, and they are in contact with each other. A positively charged rod R is brought close to X as shown in part (a) of the figure. Sphere Y is now moved away from X, as shown in part (b). What are the final charge states of X and Y?

X is negative and Y is positive

which of the following will increase the capacitance of a parallel-plate capacitor?

an increase in the plate area and a decrease in the plate separation AND an increase in the charge on the plates

a parallel-plate capacitor consists of a set of two parallel plates of area A separated by a distance d. this capacitor is connected to a battery that maintains a constant potential difference across the plates. a slap of dielectric material is inserted in the region between the plates and completely fills it. what changes would you observe as the dielectric is inserted

both the charge on the plates of the capacitor and its capacitance would change AND the potential difference across the plates would increase

A single current-carrying circular loop of radius R is placed next to a long, straight wire, as shown in the figure. The current in the wire pints to the right as is of magnitude I. In which direction must current flow in the loop to produce zero magnetic field at its center

clockwise

the electron-volt is a unit of

energy

an electromagnetic wave is propagating towards the west. at a certain moment, the direction of the magnetic field vector associated with the wave is pointing vertically up. what is the direction of the electric field vector

horizontal and pointing south

as the temperature of the air increases, what happens to the velocity of sound

it increases

If the rate of change of the magnetic field applied to a loop of wire is doubled, what happens to the induced emf in that loop assuming all the other parameters remain unchanged?

it is doubled

the length of a certain wire is doubled while its radius is kept constant. what is the change in the resistance of the wire

it is doubled

kirchhoff's junction rule is a statement of

law of conservation of charge

kirchhoff's loop rule is a statement of

law of conservation of energy

the wire in the figure carries a current I that is increasing with time at a constant rate. The induced emf in each of the loops is such that

loop A has clockwise emf, loops B has no enduced emf, and loop C has counterclockwise emf

Two stationary point charges q1 and q2 are shown in the figure along with a sketch of some field lines representing the electric field produced by them. What can you deduce from the sketch?

q1 is negative and q2 is positive, the magnitude of q1 is less than the magnitude of q2

In order to produce beats, the two sound waves should have

slightly different frquencies

which one of the following is not an electromagnetic wave

sound waves

For a beam of light, the direction of polarization is defined as

the direction of the electric field's vibration

which statements must be true about the surface of a charged conductor in which no charge is moving?

the electric potential is constant over the surface AND the electric field is perpendicular to the surface

Two tiny beads are 25 cm apart with no other charges or fields present. Bead A carries 10 µC of charge and bead B carries 1 µC. Which one of the following statements is true about the magnitudes of the electric forces on these beads?

the force on A is exactly equal to the force on B

a solid aluminum cube rests on a wooden table in a region where a uniform external electric field is directed straight upward. what can we say concerning the charge on the top surface of the cube?

the top surface is charged positively

Four unequal resistors are connected in a parallel with each other. Which one of the following statements is correct about this combination?

the total resistance is less than the smallest resistor

A capacitor C is connected in series with a resistor R across a battery and an open switch. If a second capacitor of capacitance 2C is connected in parallel to the first, the time constant of the new RC circuit will be

three times as large as before

an electron moving south, enters a magnetic field of a certain strength. because of the field the electron curves upward, what is the direction of the magnetic field?

towards the west

an electron is initially moving to the right when it enters a uniform electric field directed upwards, as shown in the figure. which trajectory will the electron follow in the field

trajectory Z