Ohm's Law & Electric Power

3 components of electricity

voltage, current, and resistance

voltage (V)

-potential difference between the strength of the electron supply and the electron shortage

-measure of the amount of potential energy per electric charge or Coulomb

volts (V)

units for voltage

1 Volt = Energy / Electric Charge = Joule / Coulomb = J / C

coulomb

unit of electric charge

energy

J = V * C

measure of work

joules

units for energy

voltage is _____ when two batteries are in series (stacked)

doubled

-putting batteries in parallel (next to each other) allows longer battery life

2 ways of combining resistors

series and parallel

series

electrons flow in one path in sequence through resistors

parallel

electrons divide to pass through each other

current (I)

-net flow of electrons through a material

-amount of charge passing a point per unit time

amperes (A)

-units for electric current

1 Amp = (6.24 × 10^18 electrons passing a point / second) = 1 Coulomb / second = C / s

1 C = 6.24 × 10^18 electrons

resistance (R)

-measure of a material’s opposition to the passage of electric current

-measure of the frictional force encountered by electrons as they attempt to pass through a material

R = V / I

ohms (Ω)

units for resistance

circuits

-used to induce current flow by giving it a path or closed circuit

-creating closed circuits causes the voltage to push the electrons to move

-resistors included along the path (ex: bulb)

circuit diagram

-graphical representation of electric circuit

-physical components: power source, resistive element, conductive material (wire)

power source

-orientation matters

-ex: battery

resistor

-orientation does not matter

conductor

-wire

-assumed resistance is zero

ohm’s law

V = I * R

-relates voltage, current, and resistance to each other

power

Joule’s Law: P = I * V

-work performed per unit time

The third stripe of a color code on a resistor represents the number of _____ to add after the first two digits.

zeroes

Using a multimeter, voltage must be measured in _____ to the circuit.

parallel

Using a multimeter, current must be measured in ______ with the circuit.

series

Using a multimeter, resistance must be measured in a ________ circuit.

disconnected

kirchoff’s voltage law

the algebraic sum of voltages around a closed loop in a circuit is 0

Voltage rises - voltage drops = 0

kirchoff’s current law

the current entering a junction point/node equals the sum of currents leaving a node