Chapter 6: Electrostatics

Question 1

Electrostatics is:

Answer 1

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

Question 2

Proton charge:

Answer 2

positive

Question 3

Electron charge:

Answer 3

negative

Question 4

Opposite charges exert what kind of forces?

Answer 4

attractive

Question 5

Like charges exert what kind of forces?

Answer 5

repulsive

Question 6

The SI unit of charge is the:

Answer 6

Coulomb [C]

Question 7

The fundamental unit of charge (e) is:

Answer 7

e = 1.6 X 10^-19 Coulombs

Question 8

The charge of one proton and the charge of one electron are equal to:

Answer 8

1.6 X 10^-19 Coulombs; protons are positive, electrons are negative

Question 9

Coulomb’s law gives us:

Answer 9

The magnitude of the electrostatic force F between two charges q₁ and q₂ whose centers are separated by a distance r.

Question 10

The equation used to determine the attractive or repulsive force two charges exert on one another:

Answer 10

F = kq₁q₂ / r²;

where k = 8.99 X 10⁹ NM²/C²; q₁ and q₂ are in Coulombs; r is in meters

Question 11

The direction of the force between two charges may be obtained by remembering that:

Answer 11

like forces repel and opposite forces attract

Question 12

An electric field is:

Answer 12

the electrical force on a stationary positive charge divided by the charge

Question 13

Electric fields are produced by:

Answer 13

a stationary source charge (q)

Question 14

A stationary test charge is:

Answer 14

the charge placed in the electric field

Question 15

Whether the force exerted through the electric field is attractive or repulsive depends on:

Answer 15

whether the stationary test charge and the stationary source charge are opposite or like charges

Question 16

The equation used to determine the electric field produced by a source charge at a chosen point in space:

Answer 16

E = F/q₀ = Kq/r₂;

where E is the electric field magnitude, F is the force felt by the test charge q₀, k is the electrostatic constant (8.99 X 10⁹), q is the source charge magnitude, and r is the distance between the charges.

Question 17

E = F/q₀ requires:

Answer 17

the presence of the test charge in the electric field

Question 18

E = kq/r^₂ does not require:

Answer 18

the presence of a test charge in the electric field

Question 19

The direction of the electric field vector is given as:

Answer 19

the direction a positive test charge (+q₀) would move in the presence of the source charge. If the source charge is positive, the electric field vector radiates outwards. If the source charge is negative, the electric field vector radiates inwards.

Question 20

A collection of charges in an electric field will exert a net electric field at a point in space that is equal to:

Answer 20

the vector sum of all three of the electric fields

Question 21

The equation used to determine the total electric field at a chosen point in space:

Answer 21

E_total = Eq₁ + Eq₂ + Eq₃ + …

Question 22

The magnitude of the force exerted on a test charge place in an electric field can be calculated using the equation:

Answer 22

F = q₀E; where q₀ is the charge of the test charge and E is the magnitude of the electric field

Question 23

Electric potential energy is:

Answer 23

the potential energy related to the relative position of one charge with respect to another charge or to a collection of charges. It is the work necessary to move a test charge from infinity to a point in space in an electric field surrounding a source charge.

Question 24

The equation used to calculate the electric potential energy between two charges separated in space:

Answer 24

U = kqQ / r

where k = 8.99 X 10⁹, q is one charge, Q is a second charge, and r is the distance between them

Question 25

Electric potential energy is positive when:

Answer 25

the charges are like charges

Question 26

Electric potential energy is negative when:

Answer 26

the charge are opposite charges

Question 27

When unlike charges move towards each other, the electric potential energy:

Answer 27

decreases

Question 28

When unlike charges move apart from one another, the electric potential energy:

Answer 28

increases

Question 29

The electrical potential energy (U) is equal to:

Answer 29

the work (W) necessary to move a test charge from infinity to a point in space in an electric field surrounding the source charge.

Question 30

Electric potential is:

Answer 30

the ratio of the magnitude of a charge’s potential energy (U, which is equal to W) divided by the magnitude of the test charge itself. It is the electric potential energy per unit of charge

Question 31

The equation used to determine the electric potential due to a known source charge at a chosen point in space is:

Answer 31

V = W / q₀ = kQ/r

where V is he electric potential measured in volts, W is the electric potential energy of the charge, q₀ is the charge of the test charge, and Q is the magnitude of the source charge.

Question 32

1 Volte is equal to:

Answer 32

1 Joule / Coulomb

Question 33

Electric potential is a:

Answer 33

scalar quantity

Question 34

For a collection of charges, the total electric potential at a point in space is:

Answer 34

the scalar sum of the electric potential due to each charge (V_total = Vq₁ + Vq₂ + Vq₃ + ^{_{scalar sum}})

Question 35

The equation used to determine the potential difference between two points in space:

Answer 35

V_b - V_a = W_ab/q₀

where W_ab is the work needed to move a test charge q₀ through an electric field from point a to point b.

Question 36

Positive charges move spontaneously from:

Answer 36

high voltage to low voltage

Question 37

Negative charges move spontaneously from:

Answer 37

low voltage to high voltage

Question 38

The equipotential line is the one in which:

Answer 38

the potential at every point is the same (the potential difference between any two points on the equipotential line is zero)

Question 39

Work needed to move a test charge from point a to point b through an electric field depends only on:

Answer 39

the the potential difference; the path taken is negligible and does not matter

Question 40

The electric dipole results from:

Answer 40

two equal and opposite charges being separated a small distance from each other

Question 41

The equation used to determine the electric potential at a point in space due to an electric dipole:

Answer 41

V = (kp/r²)cosØ

where p is the dipole moment, r is the distance between the point in space and the midpoint of the dipole, and theta is the angle between r and the dipole

Question 42

The equation used to determine the electric field due to an electric dipole along the perpendicular bisector of the dipole:

Answer 42

Question 43

The equation used to determine the net torque experienced by an electric dipole about the center of the dipole axis due to an external electric field:

Answer 43

t = pE(sinØ)

where p is the magnitude of the dipole moment, E is the magnitude of the electric potential, and Ø is the angle the dipole moment makes with the electric field

Question 44

The magnitude of the dipole moment (p) is equal to:

Answer 44

p = qd

Question 45

The torque place on a dipole will cause the dipole to:

Answer 45

reorient itself by rotating so that its dipole moment (p) aligns with the electric field (E)

Question 46

In an external electric field, an electric dipole will experience a net torque until:

Answer 46

it is aligned with the electric field vector

Question 47

An electric field will not induce any translational motion regardless of:

Answer 47

its orientation with respect to the electric field vector.