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Current
The Flow of charge through a conductor.
What is Current measured in?
Amperes
Current Density Equation
J=I/A
Kirchhoff's Junction Law
The current is the same everywhere in a circuit with no junctions. 2)The sum of currents entering a junction equals the sum leaving.
Resistivity
Is an electrical property of a material.
Resistance
is a property of a specific wire or circuit element based on the material of which it is made and its size and shape.
Ohm's Law
The change in V/R
Current
Motion of charges
Voltage Across Capacitors....
Adds up to the net voltage
If Capacitors are in parallel...
They will have the same voltage
When adding two resistors in series...
The resistance is being increased
When adding two resistors in parallel...
The Resistance is being decreased
What quantity is represented by the symbol J ?
Current Density
The electron drift speed in a typical current-carrying wire is?
Extremely Slow (≈ 10^–4 m/s).
All other things being equal, current will be larger in a wire that has a larger value of...
Conductivity
Electrons are the charge carriers in...
Metals
Electron Current
the number of electrons per second that pass through a cross section of the conductor.
When an conductor is in electrostatic equilibrium...
there is no electric field.
The electron current is directly proportional...
to the electric field strength.
Note that the direction of the current I in a metal is...
opposite to the direction of the electron current ie.
Current Density Units
A/m^2
Due to conservation of charge, the current in a current-carrying wire...
must be the same at all points
This complete loss of resistance at low temperatures is called
superconductivity
The unit of Resistance
Ohm
Circuits
the controlled motion through conductors and resistors
How many laws are named after Kirchhoff?
2
In an RC circuit, what is the name of the quantity represented by the symbol τ?
Time constant
The equivalent resistance for a pair of parallel resistors is?
Less than any resistor in the group
Kirchoff's loop law
The sum of all the potential differences encountered while moving around a loop or closed path is zero.
The power supplied by a battery is
P=Ie
The units of Power
Watts
The power dissipated by a resistor is
P=IV
A current carrying resistor dissipates power because...
the electric force does work on the charges
Resistors that are aligned end to end, with no junctions between them, are called
Series resistors
Resistors connected at both ends are called
parallel resistors
If a circuit is connected to the Earth through an ideal wire it is said to be...
grounded
RC Circuit
A circuit with both resistors and capacitors
Charge on the capacitor of an RC circuit is
Q0e^-t/τ
Note 
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