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

2. 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.

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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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