Resistance/Ohm's Law/Kirchhoff's Law

RESISTANCE:  a measure of the opposition to current flow  

•  the amount of current flow in a circuit depends on two things: 

1)  the potential difference of the power supply
2) the nature of the pathway through the loads 

OHM'S LAW:

• Graphing the Linear Equation for Ohm's Law from Data:

• Factors that Affect Resistance:

- Length: longer the conductor, the greater the resistance
- Cross-sectional area: the larger/thicker conductor, less resistant it has to charge flow
- Type of material: resistivity is measure of resistance of a substance
- Temperature: greater molecular motion at higher temperature increases the resistance

• SUPERCONDUCTIVITY: ability of a material to conduct electricity without heat loss due to electrical resistance.

KIRCHHOFF'S CURRENT LAW:
The total amount of current into a junction point of a circuit equals the total current that flows out of that same junction.

KIRCHHOFF'S VOLTAGE LAW:
The total of all electrical potential decreases in any complete circuit loop is equal to any potential increases in that circuit loop.

• In other words, there is no net gain or loss of elecric charge or energy

Kirchhoff's laws in a SERIES circuit:
VOLTAGE: Voltage must be distributed so that the sum of all voltage drops must equal this value.

VT= V1 + V2 + V3

CURRENT: The circuit only has one path to flow.

IT= I1 = I2 = I3

Kirchhoff's laws in a PARALLEL circuit:
VOLTAGE: Voltage drops have to remain the same no matter what.

VT= V1 + V2 + V3

CURRENT: the sum of the current entering junctions must equal the sum of the current exiting them.

IT= I1 + I2 + I3

RESISTANCE IN SERIES:

RT = R1 + R2 + R3 .... + RN

(N is the total number of series resistors in the circuit)

RESISTANCE IN PARALLEL:

1/RT = 1/R1 + 1/R2 + 1/R3 .... + 1/RN

You can rewatch the video on RESISTANCE :)