Physics Concepts (Electricity & Magnetism)

What are the properties of electric charge?

like charges repel, opposite charges attract

How can objects become charged?

conduction, induction, by friction

What is an electric insulator?

it inhibits the flow of electrons

What is the relationship between distance, charge, and force in Coulomb's Law?

increasing distance = decreasing force; increasing charge = increasing force

What is an electric dipole?

a set of two opposite charges of equal magnitude separated by a small distance

What is a Gaussian surface?

a fully enclosed surface

How do conductors distribute charge?

evenly throughout

How do insulators distribute charge?

locally on the surface

What is the relationship between an electric field and radius?

directly proportional to r; inversely proportional to 1/r^2

What do high and low potential mean, respectively?

positively and negatively charged

What is the magnitude of an electric field inside a solid conductor in equilibrium?

E = 0

How is charge distributed on irregularly shaped conductors?

the distribution is higher where the radius of the surface is smaller

What is the relationship between potential difference and radius?

inversely proportional to 1/r

What creates a capacitor?

two separate conductors

What is the relationship between capacitance and charge?

directly proportional to Q

What is the relationship between capacitance and potential difference?

directly proportional to V

What affects the magnitude of the current in a conductor?

magnitude of ∆V; the conductor's material

What is resistivity?

a measure of how much a material resists the flow of charges

What is conductivity?

a measure of how much a material conducts the flow of charges

What is the relationship between voltage and current?

directly proportional to I

Which direction do electrons flow in relation to current?

in the opposite direction

What happens to the current in a circuit with capacitors connected in series?

the current remains the same across each capacitor

What happens to the current in a circuit with resistors connected in series?

the current remains the same across each resistor

What happens to the current in a circuit with capacitors connected in parallel?

the current changes across each capacitor

What happens to the current in a circuit with resistors connected in parallel?

the current changes across each resistor

What happens to the voltage in a circuit with capacitors connected in series?

the voltage changes across each capacitor

What happens to the voltage in a circuit with capacitors connected in parallel?

the voltage remains the same across each capacitor

What happens to the voltage in a circuit with resistors connected in series?

the voltage changes across each resistor

What happens to the voltage in a circuit with resistors connected in parallel?

the voltage remains the same across each resistor

What are Kirchhoff's Rules?

at a junction, ∑I (in) = ∑I (out); for all closed loops, ∑∆V = 0

What is the magnitude of ε when the loop is oriented from lowest to highest potential?

+ε

What is the magnitude of ε when the loop is oriented from highest to lowest potential?

-ε

What is the magnitude of IR when the loop is oriented the same as the current?

-IR

What is the magnitude of IR when the loop is oriented opposite to the current?

+IR

What is an RC circuit?

a circuit combining a resistor and a capacitor

What is the time constant of an RC circuit?

τ = RC

What are the properties of magnets?

like poles repel, opposite poles attract

What direction do the field lines point outside a magnet?

from the north to the south pole

What direction do the field lines point inside a magnet?

from the south to the north pole

What direction does the magnetic field point when denoted with O?

outside the page

What direction does the magnetic field point when denoted with X?

into the page

What happens when the direction of the current and the magnetic field is parallel?

Fm = 0

How is the direction of the magnetic field found?

by the right-hand rule

What is the Hall Effect?

voltage is created when a magnetic field is applied perpendicular to a current

What happens when two currents are next to each other?

parallel currents attract, antiparallel (opposite direction) currents repel

What is the relationship between the magnitude of a magnetic field and radius?

directly proportional to r; inversely proportional to r^-1

What is a solenoid?

a long wire wound in a helical coil with a relatively uniform magnetic field in its center

What is a toroid?

a donut-shaped version of a solenoid

What are the properties of a toroid?

the magnetic field lines are trapped inside the core; the magnitude of the electric field is not necessarily constant within the core

What does Faraday's Law state?

a stationary magnet does not generate current; a moving magnet generates current in the loop/circle

What does electromotive force depend on?

change in the magnitude of the magnetic field; change in area; change in direction of the magnetic field relative to the normal vector

What is Lenz's Law?

a current induced by a changing magnetic field will generate a magnetic field opposing the original magnetic field

What happens during mutual inductance when the current in the primary loop is increasing?

the secondary loop has current flow in the opposite direction by Lenz's Law

What happens during mutual inductance when the current in the primary loop is decreasing?

the secondary loop has current flow in the same direction to compensate for a decreasing magnetic field

What is an RL circuit?

a circuit combining a resistor and an inductor

What is an LC circuit?

a circuit combining an inductor and a capacitor

What is an RLC circuit?

a circuit combining a resistor, an inductor, and a capacitor

What is the time constant of an RL circuit?

τ = L/R