Chapter 17: Electricity PEPS Rainier Jr/Sr High School Mr. Taylor

Electricity Electricity is the energy associated with the movement of electrons.

Electrical Charges Positive is the charge on a proton. Negative is the charge on an electron. Neutral is no charge/the charge on a neutron. Basic idea: like charges repel, unlike charges attract. The total charge on an object depends on the imbalance between positive and negative charges in that object.

Electric currents An electric current is the flow of electrons in a circuit. ◦ Conductors allow electrons to flow easily. ◦ Insulators hinder the easy flow of electrons.

Electrical fields Electrical fields are set up around charged objects ◦ The force of this field varies with charge and distance. ◦ The total force is known as electrical potential energy and is measured in volts.  High voltage = high potential energy

Electrical current When a circuit is completed a pathway for electron flow is established. The rate at which electrons flow is called electric current and is measured in amperes (amps). ◦ Electrons flow from a negative pole toward a positive pole. Direct current (DC); electrons only flow one direction Alternating current (AC); electron flow reverses direction periodically.

Electrical resistance Even good conductors offers some friction to reduce the rate at which electrons flow. This friction is referred to as electrical resistance and is measured in ohms (  ).

Ohm’s Law Voltage, current, and resistance are related by Ohm’s Law: ◦ V = IR ◦ voltage = current x resistance ◦ volts = amps x ohms

Electrical circuits Electrons can only flow in a circuit; a complete pathway from the negative side of a voltage source to the positive side of the source. Circuits can be coded by using a schematic diagram. You should know the symbols for a battery, resistor, switch, and light bulb.

Series vs Parallel circuits A series circuit only has one pathway for the flow of electrons. A parallel circuit has more than one pathway for the flow of electrons.

Electrical power The rate at which electrical energy is turned into other forms of energy is called electrical power and is measured in watts. ◦ P = I V ◦ Power = current x voltage ◦ watts = amps x volts

Fuses and circuit breakers High currents can be dangerous and can cause problems (like fire!). Fuses and circuit breakers protect us by opening the circuit when dangerously high currents flow.