CHARGES Flashcards
What is the SI unit of Charge?
Coulomb(C)
Charge cannot be created or destroyed(T/F)
True
What are insulators and Conductors?
Insulators have localized charges, do not conduct well.
Conductors distribute charges well evenly.
What is the charge for proton? electron?
proton: 1.60 x10^-19C
electron: -1.60 x10^-19C
Which one experiences faster acceleration between proton and electron and why?
electrons, due to smaller mass
What is Coulomb’s law and what does it show?
F = k(q1)(q2)/r^2
What is Coulomb’s constant(w/ units)?
k = 8.99 x 10^9 N*m^2/C^2
What other kind of “force” is analogous to Electrostatic force?
Gravitational force: Fg = Gm1m2/r^2
What is Electric field and its formula?
E is made by the source charge(Q), and can exert force on to a test charge(q), which is the charge placed in electric field. E = Fe/q = kQ/r^2
What is the difference between the two formulas: E = Fe/q and E = kQ/r^2
1st one shows how to calculate the magnitude of the electric field when an actual test charge is present and the 2nd one shows how to calculate it with only an imaginary point and not an actual charge.
What is the Electrical potential energy?
Work required to bring the test charge from infinitely far away to the particular point. Potential energy to do work by a charge related to its location.
What is the equation for Electrical potential energy and how is this equation derived?
Fe=kQq/r^2, W=Fdcos(Θ) –> W=kQq/r = dU
What does +dU mean? -dU?
\+dU = more potential energy means less stable, two like charges put together; ex. positive charge going against the electric field -dU = less potential energy means more stable, two opposite charges put together; ex. positive charge going in the same direction as the electric field.
What is Electrical Potential? Formula?
V = Potential energy per unit of charge. V = U/q
What is the difference between U and V?
U is dependent on the magnitude of the test charge because the amount of influence it experiences by the source charge’s electric field is what we are interested in.
V is not dependent on the test charge because it is solely a characteristic of the location by the source charge’s electric field.
In short, U is relative because it involves two different charges whereas V shows how much U is involved “per charge” at that specific location.
What is the formula for V when the test charge is not present?
V = kQ/r
How can dV be related to work?
Vb - Va = Wab/q
What is the tendency that charges(q) have in relation to electrical potential energy? What’s the case with positive charge(q)? negative charge(-q)?
Always towards Decreasing the U -> more stable.
dU = (-) …..W = (-)
This means: with a positive charge, dV will be negative
with a negative charge, dV will be positive.
List the formulas for: Coulomb’s law, Electrical potential energy, Electrical potential, and Electric field.
Fe = kQq/r^2 U = kQq/r E = kQ/r^2 V = kQ/r
What is Equipotential line?
Line where the Potential is the same on every point on the line, in a spherical shape.
What is electric dipole? How does it affect the V?
Measure of the separation between a positive and a negative charges that are equal, with distance “d”. The two charges will produce Electric fields and at a particular point, there will be a corresponding V value.
What is the dipole moment “p”?
p = qd(C*m)
What is the formula for electrical potential when electric dipole is present?
V = kqdcosΘ /r^2
What is perpendicular bisector of the dipole and its significance?
A plane that is perpendicular to the dipole with Θ = 90 has V = kqdcosΘ /r^2 = 0V
