Physics Ch 6. Circuits Flashcards
Current
Movement of charge that occurs between two points that have different electrical potentials, by convention defined as the movement of positive charge from a high potential end of a voltage source to a low potential end, in reality it is negatively charged particles/electrons that move in a circuit from low potential to high potential
Conductive material
Allows current to flow
Metallic conduction
Relies on uniform movement of free electrons and metallic bonds
Electrolytic conduction
Relies on ion concentration of a solution
Insulators
Materials that do not conduct a charge
Kirchhoffs laws
Express conservation of charge and energy
Kirchhoffs junction rule
States that sum of currents directed into a point within a circuit equals the sum of currents directed away from that point
Kirchhoffs loop rule
States that in a closed loop the sum of the voltage sources are always equal to the sum of the voltage drops
Resistance
Opposition to the movement of electrons through material, calculated using resistivity, length, and cross-sectional area of the material
Resistors
Conductive materials with a moderate amount of resistance that slow down electrons without stopping them
Ohms law
States that for a given resistance, the magnitude of the current through resistor is proportional to the voltage drop across the resistor
Resistors in series
Are additive in some together to create the total resistance of a circuit
Resistors in parallel
Cause a decrease in the equivalent resistance of a circuit
Resistor power dissipation
The amount of power dissipated through each resistor in a circuit is dependent on the current through the resistor and the voltage drop across the resistor
Capacitors
Have the ability to store and discharge electrical potential energy
Capacitance in parallel plates
Determined by the area of the plates and the distance between them
Capacitors in series
Cause a decrease in the equivalent capacitance of the circuit
Capacitors in parallel
Some together to create a larger equivalent capacitance
Dielectric materials
Insulators placed between the plates of a capacitor that increase capacitance by a factor equal to the materials dielectric constant, k
Ammeters
Inserted in series with a circuit to measure current, have negligible resistance
Voltmeters
Inserted in parallel in a circuit to measure a voltage drop, have very large resistances
Ohmmeters
Inserted around a resistive element to measure resistance, or self powered and have negligible resistance
Current equation
I = Q/deltaT
Kirchhoffs junction rule equation
I_intojunction = I_leavingjuction
Kirchhoffs loop rule equation
V_source = V_drop
Resistance equation
R = rho*L/A
Ohms law equation
V=IR
Voltage and cell emf equation
V = Ecell - ir_int
Definition of power equation
P = W/t/DELTAE/t
Electric power equation
P = IV = I^2R = V^2/R
Definition of capacitance equation
C = Q/V
Capacitance based on parallel plate geometry
C = epsilon_0*A/d
Electric field in a capacitor equation
E = V/d
Potential energy of a capacitor equation
U = 1/2CV^2
Capacitance with a dielectric material equation
Cprime = kappa*C
Equivalent capacitance in series equation
1/Cs = 1/C1+1/C2+1/C3…
Equivalent capacitance in parallel equation
Cp = C1+C2+C3…
