Voltage

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Voltage

• A force that pushes the current through
• Measured in volts

Resistance

• Friction that impedes the flow of current through the circuit
• Measured in Ohms
• Lower the resistance the easier it is for the electrons to pass through a material
• Can be used to convert electrical energy into useful light energy and wasted heat energy (voltage drop)
• Factors of resistance
  • Material of wire
  • Length of wire
  • Thickness of wire

Electric Circuit

• Path travelled by the electrons to deliver the energy is called an electric circuit
• And break in the circuit will stop the flow of electrons
• The current goes from the negative to positive end of the battery and the circuit should start and end at the battery
• Circuit symbols are used to show an electric circuit

Simple Circuit

• Series Circuit
  • All resistors are placed in a row
  • 1 path for electricity
  • 1 light goes out and the circuit is broken
• Parallel circuit
  • Many paths for electricity
  • 1 light goes out and the others stay on

Series Circuit

• Current flowing through each resistor is the same
• Current = $I_{total}=I_1=I_2=\dots$
• Voltage across each resistor is different
• Resistance = $R_{total}=R_1+R_2+\dots$

Parallel circuit

• Voltage across each resister is same
• Voltage = $V_{total}=V_1=V_2=\dots$
• To calculate total resistance in parallel circuit, $\frac{1}{R_{total}}+\frac{1}{R_1}+\frac{1}{R_2}+\dots$

Cell and Battery

Cell	Battery
- Single Unit Device - Typical Cell has voltage of 1.5 V	- Group of cells - Voltage can be calculated by adding voltage of individual cells