Unit 8 - Electricity

Electricity What is electricity? The flow of electric charge (either protons or electrons) This flow is called current Electric current carries energy

Current Does work Measure current using an ammeter Circuit breakers or fuses stop too much current from flowing. Types of current: Alternating (AC): direction of current goes back and forth Example: household current is AC Direct (DC): current flows in one direction. Example: battery

Electrical Conductivity Property of a substance: its ability for current to pass through Conductors- electrons come free and can move to create electrical current allow current to pass metals Insulators- electrons are tightly bound to atoms and cannot move block current Usually nonmetals, some plastics, foam or rubber Semiconductors- in between in ability to conduct current Computer chips, LED’s, some lasers

How does charge flow? Voltage-the push behind the current! Electric charge flows from high energy (voltage) to lower energy. Voltage is measured using a voltmeter All points on a wire are the same voltage. Voltage is reduced when energy is used. Supplies energy to make charges flow.

Resistance Measures how easily charges flow in a material Factors that affect resistance Thickness Thicker wire has a lower resistance Length Longer wire has more resistance

Ohm’s Law The relationship between amps, volts and ohms Current Unit: Amps Symbol: I Voltage Unit: Volts Symbol: V Resistance Unit: Ohms Symbol: R