ELECTRICITY
Charges: Atoms contain particles called protons, neutrons, and electrons.
-Protons have a positive charge.
-Electrons a negative charge.
-And neutrons a neutral charge.
Charges and Forces:
-Electric Charge: A property that causes subatomic particles to attract or repel each other.
-Electric Forces: The force of attraction or repulsion between electrically charged objects.
Charging Objects:
-Rubbing two materials together can result in transfer of electrons.
-One is left with a positive charge and the other with an equal number of negative charges.
-This process of transfer by touch is called charging by contact.
-Conduction: The contact of a neutral object to a charged object.
-Friction: Two objects rub. One becomes positively charged, one negatively.
-Induction: Charging an object without making it touch another.
-Law of Conservation of Charge: Charge cannot be created or destroyed. Only transferred.
-Static Electricity is the accumulation of excess charge.
Conductors:
-A material in which electrons can move easily in.
-Metals are the best conductors.
Insulators:
-A material in which electrons are not able to move easily.
-Plastic, rubber, and glass are good insulators.
Charges: Atoms contain particles called protons, neutrons, and electrons.
-Protons have a positive charge.
-Electrons a negative charge.
-And neutrons a neutral charge.
Charges and Forces:
-Electric Charge: A property that causes subatomic particles to attract or repel each other.
-Electric Forces: The force of attraction or repulsion between electrically charged objects.
Charging Objects:
-Rubbing two materials together can result in transfer of electrons.
-One is left with a positive charge and the other with an equal number of negative charges.
-This process of transfer by touch is called charging by contact.
-Conduction: The contact of a neutral object to a charged object.
-Friction: Two objects rub. One becomes positively charged, one negatively.
-Induction: Charging an object without making it touch another.
-Law of Conservation of Charge: Charge cannot be created or destroyed. Only transferred.
-Static Electricity is the accumulation of excess charge.
Conductors:
-A material in which electrons can move easily in.
-Metals are the best conductors.
Insulators:
-A material in which electrons are not able to move easily.
-Plastic, rubber, and glass are good insulators.
Electricity:
-Electric current: The continuous flow of electric charge. Measured in Amps (a).
-Electrons in metals are in constant motion.
-When electrons flow, they continue random movement but also drift in the direction of the current.
Circuit:
-A circuit is a closed path through which electrons can flow.
-Scientists usually draw electric circuits using symbols.
-Battery, Light bulb, Switch, and Resistor.
-A closed switch means that the circuit through the switch is connected. This is called a closed circuit.
-A broken wire or an off switch both leave gaps in a circuit. This is called an open circuit.
-Electric current: The continuous flow of electric charge. Measured in Amps (a).
-Electrons in metals are in constant motion.
-When electrons flow, they continue random movement but also drift in the direction of the current.
Circuit:
-A circuit is a closed path through which electrons can flow.
-Scientists usually draw electric circuits using symbols.
-Battery, Light bulb, Switch, and Resistor.
-A closed switch means that the circuit through the switch is connected. This is called a closed circuit.
-A broken wire or an off switch both leave gaps in a circuit. This is called an open circuit.
Electricity:
-An electric field surrounds every electric charge and exerts the force that causes other electric charges to be attracted or repelled.
-Any charge placed in that field will be pushed or pulled.
Voltage:
-Causes current to flow through an electrical circuit.
-Measured in Volts (v)
-A voltage source (battery or generator) is required to maintain the electrical potential in a circuit.
Resistance:
-Opposition the flow of electrons.
-Electricial energy is converted to thermal energy and light.
-Measured in ohms.
-Resistance depends on the conductor (wire)
-Thickness: Less resistance in thicker wires.
-Temperature: Less resistance at low temperatures.
-Length: Less resistance in shorter wires.
Circuits:
-Series: Current travels in a single path.
-One break stops the flow of current.
-Current is the same throughout the circuit.
-Lights are equal brightness.
-Each device receives a fraction of the total voltage.
-The more lights added, the dimmer they get.
-Parallel: Current travels in multiple paths.
-One break doesn't stop the flow.
-Current varies in different branches.
-Takes path of least resistance.
-"Bigger" light would be dimmer.
-Each device receives the total voltage.
-No change when lights are added.
-An electric field surrounds every electric charge and exerts the force that causes other electric charges to be attracted or repelled.
-Any charge placed in that field will be pushed or pulled.
Voltage:
-Causes current to flow through an electrical circuit.
-Measured in Volts (v)
-A voltage source (battery or generator) is required to maintain the electrical potential in a circuit.
Resistance:
-Opposition the flow of electrons.
-Electricial energy is converted to thermal energy and light.
-Measured in ohms.
-Resistance depends on the conductor (wire)
-Thickness: Less resistance in thicker wires.
-Temperature: Less resistance at low temperatures.
-Length: Less resistance in shorter wires.
Circuits:
-Series: Current travels in a single path.
-One break stops the flow of current.
-Current is the same throughout the circuit.
-Lights are equal brightness.
-Each device receives a fraction of the total voltage.
-The more lights added, the dimmer they get.
-Parallel: Current travels in multiple paths.
-One break doesn't stop the flow.
-Current varies in different branches.
-Takes path of least resistance.
-"Bigger" light would be dimmer.
-Each device receives the total voltage.
-No change when lights are added.
Questions:
1. What type of charge do protons have? (see student solutions)
2. What does voltage do? (see student solutions)
3. Give examples of insulators.
4. What is the difference between a series and parallel circuit?
1. What type of charge do protons have? (see student solutions)
2. What does voltage do? (see student solutions)
3. Give examples of insulators.
4. What is the difference between a series and parallel circuit?
This whole section is packed with light bulb applications. From conductors and insulators to circuits. We have conductors and insulators in our houses, cars, almost everything we use! And circuits are everywhere too. When you flip a light switch, you are dealing with a circuit.