Physics

Front 1

Two nuclei each contain two protons and exert a force 4 N on each other. If we transfer a proton from one of these nuclei to the other, the force on each nucleus is now reduced to 3 N.

Back 1

True

Front 2

Two neutral objects cannot attract each other electrically because theyy have no excess charge.

Back 2

False

Front 3

When electric field lines are curved, the electric field at any point is tangent to the field line at that point.

Back 3

True

Front 4

Electric field lines begin on negative charges and end on positive charges.

Back 4

False

Electric field lines begin on positive charges and end on negative charges.

Front 5

The more closely electric field lines are packed together, the stronger the field.

Back 5

True

Front 6

Two infinite parallel plastic sheets contain equal negative charge densities uniformly spread over their surfaces. The electric field is zero everywhere between these sheets, not just midway between them.

Back 6

True

Front 7

It is impossible for any object to have a charge of 7.5 e.

Back 7

True

Front 8

Two protons slightly separated from one another form an electric dipole.

Back 8

False

Front 9

If two point charges exert a force of 1 N on each other when they are 3 cm apart, they will exert a force of 1/25 N when they are 15 cm apart.

Back 9

True

Front 10

Suppose you have two positive point charges and want to move them closer together. To do the least amount of work, you should move them directly toward each other; any other path will require more work because the charges must move through a greater distance.

Back 10

False

Front 11

Two equal positive charges are separated by a fixed distance. If you put a third positive charge midway between these two charges, its electrical potential energy (relative to infinity) is zero because the electrical forces due to the two fixed charges just balance each other.

Back 11

False

Front 12

You want to put an electron somewhere between the plates of a parallel plate capacitor so that it will have the maximum electrical potential energy relative to one of the plates. The best place to put it is at the inner surface of the negative plate.

Back 12

True

Front 13

Suppose you have to point charges, +Q and -q. As you pull them farther and farther apart, you increase the potential energy of this system relative to infinity.

Back 13

True

Front 14

If the electric field is zero everywhere inside a region of space, the potential must also be zero in that region.

Back 14

False

Front 15

If the electric potential in a region is constant, the electric field must be zero everywhere in that region.

Back 15

True

Front 16

The potential is zero on the surface of a conductor in electrostatic equilibrium.

Back 16

False

Front 17

When the electric field is zero at a point, the potential must also be zero there.

Back 17

False

Front 18

If the potential is constant on a surface, then any electric field present can only be perpendicular to that surface.

Back 18

True

Front 19

If an object is at zero potential, it must be uncharged.

Back 19

False

Front 20

Two equal but opposite charges are held a distance D apart, and a third point charge Q is placed midway between them. When Q is released it will remain at rest because its potential energy is zero at the midpoint.

Back 20

False

Front 21

Four charged particles (two having a charge +Q and two having a charge -Q) are distributed on the xy-plane, as shown below. Each charge is equidistant from the origin. The voltage is zero at infinity. The voltage at location P, which is on the z axis is, _.

Back 21

Zero

Front 22

The capacitance of a capacitor depends on _.

Back 22

None of these

Front 23

The capacitance of a capacitor does not depend on _.

Back 23

The charge on it.

The potential difference across it.

The energy stored in it.

Front 24

Suppose a region of space has a uniform electric field, directed toward the right, as shown in the figure. Which statement is true?

Back 24

The voltage at points A and B are equal, and the voltage at point C is lower than the voltage at point A.

Front 25

If the voltage at a point in space is zero, then the electric field must be _.

Back 25

Impossible to determine based on the information given.

Front 26

A parallel-plate capacitor having circular plates of diameter D and a distance d apart stores energy U when it is connected across a fixed potential difference. If you want to triple the amount of energy stored in this capacitor by changing only the size of its plates, the diameter should be changed to _.

Back 26

D square root of 3.

Front 27

As current flows through a uniform wire, the wire gets hotter because the electrons slow down and therefore transform their lost kinetic energy into thermal energy in the wire.

Back 27

False

Front 28

When current is flowing in a metal, the electrons are moving at nearly the speed of light.

Back 28

False

Front 29

In the metal wires of a circuit, the electron current i flows from the negative to the positive end of a battery, but the current I flows from the positive to the negative end of a battery.

Back 29

True

Front 30

If a one-amp current is flowing in a wire, one electron per second flows through this wire.

Back 30

False

Front 31

The charge carriers in metals are electrons, but this is not necessarily true for other types of materials.

Back 31

True

Front 32

If there is an electric field inside of a conductor, then the current must be flowing through this conductor.

Back 32

True

Front 33

The direction of the current I in a metal wire is the same as the direction of the internal electric field in the wire, but it is opposite to the direction the electrons are moving.

Back 33

True

Front 34

If you double the diameter of a cylindrical wire, you double its conductivity but reduce its resistivity by one half.

Back 34

False

Front 35

Why is it that electrons rather than positive ions flow from a wire?

Back 35

The positive ions are locked into the crystalline structure.

Front 36

Where does the energy go that an electron has gained from the electric field when the electron passes through a conductor that has resistivity?

Back 36

Heat

Front 37

Which has the higher resistance, a piece of wire with diameter d or a piece of wire the same length, composed of the same material, but having a diameter 2d?

Back 37

The piece of wire with diamter d has the higher resistance.

Front 38

Copper wire #1 has length L and radius b. Copper wire #2 has length 2L and raidus 2b. Which statement is true?

Back 38

The total resistance of wire #1 is twice as high as that of wire #2.

Front 39

A current flowing through a copper wire (which is connected to a battery) is due to _.

Back 39

Electrons being accelerated by an electric field.

Front 40

If the length and diameter of a wire of circular cross section are both doubled, the resistance is _.

Back 40

Halved

Front 41

Ohm's law is a fundamental law of physics and is therefore obeyed by all materials.

Back 41

False

Front 42

The high potential end of a resistor is the end at which the current enters it.

Back 42

True

Front 43

If a 75 W bulb and a 100 W bulb are connected in series across a 120 V outlet, the 75 W bulb will dissipate 75 W of power and the 100 W bulb will dissipate 100 W of power.

Back 43

False

Front 44

When a potential difference of 10 V is placed across a certain solid cylindrical resistor, the current through it is 2.0 A. If the diameter of this resistor is now tripled, the current will be 18 A.

Back 44

True

Front 45

The potential across the terminals of a store-bought 1.5 V AAA battery always remains at 1.5 V unless the battery has gone dead.

Back 45

False

Front 46

In a discharging RC circuit, it takes one time constant for the capacitor to discharge completely.

Back 46

False

Front 47

Of voltmeters and ammeters, which is/are connected in series?

Back 47

Ammeters

Front 48

A circuit has a branch in it. If the current in each of thw two paths that leave the branch is 3 mA, how much current does the wire coming into the branch carry?

Back 48

6 mA

Front 49

Which will drain a battery faster, a circuit with a resistance of 10 ohms or a circuit with a resistance of 1 ohm?

Back 49

1 ohm

Front 50

A circuit requires a 500 ohm resistor, but all that is available are 1 kilo ohm resistors. If the 1 kilo ohm resistors are in abundant supply, how can they be combined to achieve the desired resistance?

Back 50

2 in parallel

Front 51

Draw a circuit with two batteries, a resistor between them, and a capacitor in parallel with the resistor. The batteries are connected negative pole to positive pole.

Back 51

A