Presentation on theme: " The continuous flow of electrons is current. Measured in amps (A). Two types of current 1. Direct current (DC) – electrons flow in only one direction."— Presentation transcript:
The continuous flow of electrons is current. Measured in amps (A). Two types of current 1. Direct current (DC) – electrons flow in only one direction. 2. Alternating Current (AC) – flow of electrons keeps switching directions.
Electrons flow due to a difference in electrical potential energy (EPE) of charges ◦ Charges flow from higher potential energy to lower potential energy ◦ Potential difference, or Voltage, is the difference of EPE between two places in an electric field.
Electrons flow due to a difference in electrical potential energy (EPE) of charges ◦ Voltage is measured in volts (V), which are joules per coulomb. ◦ The greater the voltage, the greater the “push” on the electrons.
As electrons flow through materials, they collide with other electrons and ions, losing energy and slowing current. This opposition to flow of electricity in a materials is its resistance. Anything that electricity flows through has resistance.
Measured in ohms (Ω). Resistance of a material is affected by its: 1. Thickness: thicker = less resistance 2. Length: Longer = more resistance 3. Temperature: Warmer = more resistance
Resistance, current and voltage are related (Ohm’s Law): I = current, V = Voltage, R = resistance IR V
Example 1) What is the resistance of a headlight that draws 3.0 A of current from a 12 V battery? Example 2) What is the voltage needed to produce a current of 3 amps through 3 Ω? Example 3) What is the current running through 6 V battery connected to a light bulb with a resistance of 1.5 Ω?
Conductors have low resistance and insulators have high resistance. Semiconductors will conduct electricity in certain situations Superconductor is a material that has almost zero resistance when cooled to low temperatures.