Integrated Science C Mrs. Brostrom Electricity Integrated Science C Mrs. Brostrom

Objectives: Explain the relationship among voltage, current and resistance in a simple series circuit. Explain how electricity is used to produce heat and light in incandescent bulbs and heating elements.

Electricity Electricity is energy made available from the flow of electrons. Like charges repel Opposite charges attract - - - - + + +

Current Current is the rate of flow of electricity. Measured in amperes (Amps) Battery is an example of direct current (DC)- charges always move from one terminal to the other in the same direction Alternating current (AC)- current changes directions at regular intervals

Voltage The potential difference is the change in the electrical potential energy of a changed particle divided by its charge Measured in Volt (V) Also called voltage Ex.) Batteries 1.5-12V Electrochemical cells that convert chemical energy into electrical

Resistance Resistance is a measure of the degree to which a substance impedes the flow of electric current induced by voltage. measured on Ohms (Ω) Used to control current Good conductors have a low resistance metals Good insulators have a high resistance Rubber, plastic Friction causes electric current to be dissipated as heat

Ohm’s Law V R I The current through a conductor between two points is directly proportional to the potential difference across the two points Resistance (R) = Voltage (V) / Current (I) The greater the battery voltage (potential difference), the greater the current If the voltage of the battery is doubled, the current would be doubled The greater the resistance, the less the current If the resistance was doubled, the current would be cut in half

How Does a Light Bulb Work? Electrical current passes through the lead-in wires to the filament The filament is heated until it emits light The resistance of the filament determines how bright the bulb will be 40W bulb has more resistance than a 100W bulb

Circuits A circuit is a closed path through which an electric current flows or may flow. Series circuits contain a power source that is connected to two or more components, one after the other If the circuit is broken, none of the components receive the current Only one path for the current to follow Parallel circuits contain a power source directly connected to two or more components. If the circuit is broken, only the component among the path whose path is broken stops receiving current Multiple paths for the current to follow

SERIES CIRCUIT PARALEL CIRCUIT Voltage is the same for each device The current does not have to be the same Voltage is divided across the devices Current in each device is the same Resistance may be different Therefore, voltage may be different

Quiz Time: How Does a Light Bulb Work? Electrical current passes through the lead-in wires to the filament The filament is heated until it emits light

Quiz Time: What is the relationship among voltage, current and resistance in a simple series circuit? Resistance (R) = Voltage (V) / Current (I) The greater the battery voltage (potential difference), the greater the current If the voltage of the battery is doubled, the current would be doubled The greater the resistance, the less the current If the resistance was doubled, the current would be cut in half