Chapter 5: Electrostatics and Magnetism

When placed one meter apart, which will experience a greater acceleration: one coulomb of electrons or one coulomb of protons

Electrons will have greater acceleration because they are subject to the same amount of force but with smaller mass

Conductors

Allow free and uniform passage of electrons when charged

When placed one meter apart, which will experience a greater acceleration: one coulomb of electrons or one coulomb of protons

Electrons will have greater acceleration because they are subject to the same amount of force but with smaller mass

Conductors

Allow free and uniform passage of electrons when charged

Insulators

resist movement of charge and will have localized areas of charge that do not distribute over the surface of the material

What is the net charge of an object with one coulomb of electrons and 3 moles of neutrons

-1C because neutrons do not contribute charge

What is the electric field midway between two negative charges in isolation

0, the fields will cancel out

What direction does negative electrostatic force point? what direction does positive electrostatic force point?

Points from one charge to another (attractive)

Points from one charge away from the other (repulsive)

How do distance and charge related to electrostatic force and electric field

Electrostatic force is related to the charge and inverse square of distance. Electric field does not depend on test charge but still has inverse distance squared

How does the change in electric potential from -4J to -7J reflect on the stability of the system

decrease in the potential energy means it has become more stable

Compare electric potential and coulombs law to gravitational potential energy and universal law of gravitation

Electric potential is coulombs law multiplied by distance and gravitational potential energy is universal law of gravitation multiplied by distance

how does electric potential energy change between two particles as the distance between them increases

Electric potential energy decreases as distance increases if they are the same charge.

If they are opposite charge then the potential increases as distance increases

What is the difference between electric potential and voltage

Electric potential is the ratio of charge’s electric potential energy to the magnitude of the charge

Voltage is the measure of change in electric potential between two points which can indicate a tendency to move in one direction or another

How will a charge that is placed at a point of zero electric potential move relative to a source charge

it will move to minimize potential energy, how the charge moves depends on the charge of the source and test charge

T or F: The units of electric potential energy and electric potential are different

True, Electric potential energy is Joules and Electric potential is Volts

Equipotential lines

Sets of points within space where the potential difference between any two points is zero, concentric spheres around a source charge

Electric dipole

Separation of charge within a molecule such that there is a permanent temporary region of equal and opposite charges at a particular distance

What is the voltage between two points on an equipotential line? will this voltage cause a charge to move alone the line?

No voltage so there is no acceleration along the line but there could be movement between equipotential lines

Why is the electric potential at points along the perpendicular bisector of a dipole zero?

everything cancels out but mathematically the electric potential depends on the plane perpendicular to the axis and in this case the angle is 90 so cos(90) = 0

What is the behavior of an electric dipole when exposed to an external electric field?

A dipole will rotate within the field so that its dipole moment aligns with the field

What are the requirements for a nonzero electric field, nonzero magnetic field, and nonzero magnetic force

Need a charge

Need a moving charge

Need an external magnetic field acting on a moving charge in an direction except parallel

Which would experience a larger magnetic field: an object placed 5 meters to the left of a current carrying wire or an object placed in the center of a circle with radius of 5 meters (assume current constant is 4pi x 10^-7

the loop will have a higher current.

looking at the equations we can see that the equation for a loop does not have pi in the denominator which means if everything else is the same, the loop will have a larger field.

if the electric field at a distance r away from the charge Q is 36 N/C what is the ratio of electric fields at r, 2r, and 3r

36:9:4

E= kQ/r²

36/1², 36/2², 36/3²

A positive charge of +Q is at point R, a distance d away from another charge +2Q at point S. if A is located midway between R and S and B is located d/2 away from +2Q (on same line) which direction will a positive charge move if placed in A or B

towards +Q if at A and away from +2Q if at B

Two parallel conducting plates are separated by a distance d. One plate has a charge of +Q and the other -Q. The voltage between the two plates is 12V. if a 2uC charge is released from rest from the positive plate, how much kinetic energy will it have when it reaches the negative plate?

2.4×10^-5 J

W = dU = qdV

dU = (2×10^6C)(-12V)

What is the work required to move a particle along a bisector

0

A magnetic field a distance r away from a wire is 10T. How does the magnetic field change at r if a second wire is placed 2r away from the original wire (so r is in the middle) and has a current double that of the original wire flowing in the opposite direction

30T

If drawn out, the magnetic fields will be facing the same direction so they will sum

a 9V battery is used to move a 2 C charge, how much work is done by the battery

18J

dV = W/q

9 = W/2

A proton and alpha particle (helium nucleus) repel each other with a force of F while they are 20nm away. if each particle combines with 3 electrons, what is the magnitude of the new force between them

F

The charges will change by the same amount so the end result is the same

A moving charge is placed in an external magnetic field and circulates counterclockwise in the plane of the paper. what direction is the magnetic field pointing

Out of the page

A dipole is placed in an electric field and is allowed to come to equilibrium. what would happen if the electric field were suddenly reversed

No rotation will occur, it is still in parallel with the field