Electrostatics and Magnetism

Question 1

What is electrostatics?

Answer 1

the study of stationary charges and the forces that are created by and which act upon these charges

Question 2

What is grounding?

Answer 2

the act of returning charge to the earth

Question 3

What is the coulomb?

Answer 3

fundamental unit of charge

e = 1.60x10-19 C

Question 4

What is the charge of a proton and electron

Answer 4

1 C each but protons are positive, electrons negative

Question 5

What is an insulator?

Answer 5

an object that will not easily distribute a charge over its surface and will not transfer that charge to another neural object very well

Question 6

What is a conductor?

Answer 6

an object where the charges will distribute evenly on the surface and can transfer charges well

Question 7

What is Coulomb’s Law?

Answer 7

Fe = kq1q2/r^2
Fe = magnitude of the electrostatic force
k = Coulomb's constant = 8.99 x 10^9
q1/q2 = magnitudes of the charges
r = distance between the charges

Question 8

What is the electric fields?

Answer 8

fields exert forces on other charges that move through their space

Question 9

Test charge vs source charge

Answer 9

Test charge (q) - the charge placed in the electric field
Source charge (Q) - the charge creating the electric field

Question 10

What is the equation for calculating an electric field?

Answer 10

E = Fe/q = kQ/r^2
E = electric field magnitude in N/C
Fe = magnitude of the force felt by the test charge q
k = electrostatic/Coulomb's constant
Q = source charge magnitude
r = distance between charges

Question 11

What are field lines?

Answer 11

imaginary lines that represent how a positive test charge would move in the presence of the source charge

Question 12

What is electric potential energy?

Answer 12

stored energy that comes from the relative position of one charge with respect to another charge, or collection of charges

Question 13

What is the electric potential energy equation?

Answer 13

U = kQq/r
U = electric potential energy
k = electrostatic/Coulomb's constant
Q = source charge magnitude
q = test charge magnitude
r = distance
like charge will produce positive U and unlike charges are -U

Question 14

What change in potential energy would make a system for stable?

Answer 14

A decrease so 5 J —> 2J or -4 J —> -7 J

Question 15

What is electric potential and its equation?

Answer 15

the ratio of the magnitude of a charge's electric potential energy to the magnitude of the charge itself
V = U/q = kQ/r
V = electric potential in volts (J/C)
U = potential energy
q = test charge
k = coulombs constant
Q = source charge
r = distance

Question 16

What potential difference and it’s equation?

Answer 16

the difference between electric potentials at two points, aka voltage
deltaV = Vb - Va = Wab / q
Wab = work needed to move a test charge q through an electric field from point a to point b

Question 17

What is an equipotential line?

Answer 17

a line on which the potential at every point is the same

Question 18

What is an electric dipole?

Answer 18

a molecule that results from two equal and opposite charges being separated by a small distance d from each other

Question 19

What is the equation for dipole moment?

Answer 19

p = qd
p = dipole moment

Question 20

Equation for electric potential of a dipole

Answer 20

V = kqd/r^2 * costheta

Question 21

What is the perpendicular bisector of the dipole?

Answer 21

an important equipotential line to be aware of is the plane that lines halfway between +q and -q

Question 22

What is the equation for the magnitude of an electric field on a perpendicular bisector?

Answer 22

E = k x p/r^3

Question 23

Equation for torque of the dipole

Answer 23

T = pEsintheta

Question 24

What is a magnetic field?

Answer 24

a field that can act on charges and was created by a moving charge

Question 25

What is the unit for magnetic field strength?

Answer 25

Tesla (T) = N*s/m*C

Question 26

What are diamagnetic materials?

Answer 26

material made of atoms with no unpaired electrons and have no net magnetic field

Question 27

What are paramagnetic materials?

Answer 27

material made of atom that have unpaired electrons and a magnetic dipole moment; become weakly magnetized in presence of an external magnetic field; Al, Cu, Au

Question 28

What are ferromagnetic materials?

Answer 28

material made of atom that have unpaired electrons and a magnetic dipole moment; become strongly magnetized when exposed to an external magnetic field; iron, nickel, cobalt

Question 29

What is the equation for the magnetic field of a long straight wire?

Answer 29

``` B = mu0I/2pir B = magnetic field r = distance of the magnetic field from the wire mu0 = 4pi x 10^-7 I = current ```

Question 30

What is the equation for the magnetic field of a circular wire loop?

Answer 30

``` B = mu0I/2r B = magnetic field r = distance of the magnetic field from the wire mu0 = 4pi x 10^-7 I = current ```

Question 31

What is Lorentz force?

Answer 31

sum of electrostatic and magnetic forces

Question 32

What is the equation for magnetic force?

Answer 32

F(subB) = qvBsintheta

Question 33

What is the equation for magnetic force on a straight wire?

Answer 33

F(subB) = ILBsintheta