Electrostatics and Magnetism

Question 1

fundamental unit of charge (e); charge of protons and electrons (but positive and negative)

Answer 1

e = 1.60 x 10^-19 C (coulomb)

Question 2

quantifies magnitude of electrostatic force between two charges

Answer 2

Coulomb’s law

Question 3

Coulomb’s law

Answer 3

F(e) = (k q1 q2) / r^2

where:
k = Coulomb’s constant (8.99 x 10^9 N*m^2/C^2)
q1 and q2 = magnitude of charges
r = distance between charges

Question 4

Coulomb’s constant (k)

Answer 4

k = 8.99 x 10^9 N*m^2/C^2

Question 5

generated by every charge, and exert force on other charges

Answer 5

electric field

Question 6

electric field (E)

Answer 6

E = F(e) / q = kQ / r^2

where:
q = test charge
Q = source charge
F(e) = magnitude of force felt by point charge
k = Coulomb’s constant (8.99 x 10^9 N*m^2/C^2)
r = distance between charges

Question 7

used to represent electric field vectors for a charge; point away from a positive charge and point toward a negative charge the denser the line, the stronger the field

Answer 7

field lines

Question 8

the work necessary to move a test charge from infinity to a point in space in an electric field surrounding a source charge; if like charges, then U will be positive; if unlike charges, then U will be negative

Answer 8

electric potential energy (U)

Question 9

electric potential energy (U)

Answer 9

U = kQq / r

where:
k = Coulomb's constant (8.99 x 10^9   N*m^2/C^2)
Q = source charge
q = test charge
r = distance between charges

Question 10

ratio of electric potential energy per unit charge, measured in volts (V)

Answer 10

electric potential (V)

Question 11

electric potential (V)

Answer 11

V = U / q = kQ / r

where:
k = Coulomb’s constant (8.99 x 10^9 N*m^2/C^2)
Q = source charge
r = distance between charges

Question 12

essential electrostatic equations and derivations:

Answer 12

where:

k = Coulomb’s constant (8.99 x 10^9 N*m^2/C^2)

Question 13

the change in electric potential that accompanies the movement of a test charge from one position to another

Answer 13

potential difference (voltage)

Question 14

potential difference (voltage)

Answer 14

∆V = V(b) - V(a) = W(ab) / q

where:
W(ab) = work needed to move a test charge q through an electric field from point a to b

Question 15

designate the set of points around a source charge or multiple source charges that have the same electric potential; always perpendicular to electric field lines

Answer 15

equipotential line

Question 16

as a charge is moved from one equipotential line to another work is ____ (done/not done)

Answer 16

work is done

Question 17

as a charge is moved along the same equipotential line work is ____ (done/not done)

Answer 17

work is not done

Question 18

generated when two charges with opposite signs are separated by a fixed distance (d); in an electric field, will experience a net torque until it aligns with the electric field vector

Answer 18

electric dipole

Question 19

the product of charge and separation distance

Answer 19

dipole moment (p)

Question 20

dipole moment (p)

Answer 20

p = qd

where:
q = test charge
d = separation distance

Question 21

net torque on a dipole (𝜏)

Answer 21

𝜏 = pE sin θ

where:
p = magnitude of dipole moment
E = magnitude of uniform external electric field
θ = angle the dipole moment makes with the electric field

Question 22

created by magnets and moving charges; SI unit is tesla (T; 1T = 1000 gauss)

Answer 22

magnetic field

Question 23

possess no unpaired electrons and are slightly repelled by magnet

Answer 23

diamagnetic materials

Question 24

possess some unpaired electrons and become weakly magnetic in an external magnetic field

Answer 24

paramagnetic materials

Question 25

possess some unpaired electrons and become strongly magnetic in an external magnetic field

Answer 25

ferromagnetic materials

Question 26

magnetic field at distance r from a wire (B)

Answer 26

B = μ(o)*I / 2πr

where:
μ(o) = permeability of free space
I = current through wire

Question 27

permeability of free space (μ(o))

Answer 27

μ(o) = 4π x 10^-7 T*m/A

Question 28

sum of electrostatic and magnetic forces acting on a body

Answer 28

Lorentz force

Question 29

may be exerted on a charge when it moves in a magnetic field

Answer 29

magnetic force (F(B))

Question 30

magnetic force (F(B))

Answer 30

F(B) = qvB sin θ

where:
v = magnitude of velocity
B = magnitude of magnetic field
θ = smallest angle between velocity and magnetic field vectors (v and B)

Question 31

for a straight wire, magnitude of force created by external magnetic field (F(B))

Answer 31

F(B) = ILB sin θ

where:
I = current
L = length of wire in field
θ = angle between L and B