Post on 11-Oct-2020
ELECTRICITY SPS10. Students will investigate the
properties of electricity and magnetism.
a. Investigate static electricity in terms of
• Friction
• Induction
• Conduction
b. Explain the flow of electrons in terms of
• Alternating & direct current
• The relationship among voltage, resistance and current
• Simple series & parallel circuits
Overview ELECTRICITY
Static Electricity Circuits Currents Voltage Resistance
Direct
Alternating
Series
Parallel
Induction
Conduction
Friction
Essential Questions
• What does it mean when something is electrically charged?
• How can objects become electrically charged? • Why can small birds sit on high-voltage power lines? • What characteristics of material make it a good
conductor or insulator? • Why are insulators attracted to charged objects? • Why are alternating currents commonly used in
household applications?
We Take It For Granted!
• Look around the room… • How many objects, devices or appliances
require electricity? • Think about your homes….how many things
require electricity? • What happens when there’s a power outage? • Our lives are put on hold! Why? • We are extremely dependent on
ELECTRICITY!
Electricity Origins?
• Where does it come from? • Power plants • Who makes it? • Nobody! It is not made…it’s converted! • How is it converted? • The force of steam is converted into mechanical
energy which causes a turbine (a huge wheel thingy) to rotate. The turbine is connected to an electrical generator that produces current (electricity).
• How does it get to your home/school? • It travels along wires to your home/school.
Static Electricity • What happens when you drag your feet on
carpet and then touch a doorknob? • You get a SHOCK! • Why? • Walking across the carpet causes electrons to
leave the carpet and enter your body. • When you touch the metal handle, the extra
electrons jumped from your hand to the metal. • When the electrons move from one place to
another, energy is transferred.
Transfer of Electric Charge
• Static electricity charges can build up in three ways: – _________________ – _________________ – _________________
Transfer of Electric Charge
• Charging by _______________ is the acquiring of charges when an object that has an opposite charge is ___________.
• Charging by _______________ is the acquiring of charges by _____________. If a charged object touches a neutral object, ____________ are ______________.
• Charging by _______________ is the acquiring of charges by having objects ___________ across each other.
Electric Current • The ____________ of __________ from one
place to another is called _________________. • Electric current is measured in _____________. • An ampere tell us how much current is moving
past a point in a circuit in one second. • One ampere is equal to __________ electrons
per second. • Ampere may be shortened and called the ____.
Circuits • When electrons travel in a current, the
path they follow is called a ___________. • The circuit begins at the power source to
the _______ and back to the power source.
• If the circuit is unbroken, it is _________ • If the circuit broken, it is ________.
CLOSED OPEN
How To Draw A Circuit
• Cell (power source)
• Wiring
• Closed switch
• Open switch
• Bulb
Conductors & Insulators
• Let’s remember…. • Conductors conduct electricity: _______ • Insulators don’t: __________________ • Not all conductors allow electricity to pass
through them in the same way. • Not all insulators slow down electricity in
the same way
Resistance • A measure of how hard or how easy it is for
electric current to flow through a material. • Measured in _______. • Causes electrical energy to change into ______
and _________ energy. • Depends on three things
– _____________ – _____________ – _____________
Resistance
• Example: Think of 2 water hoses. One has a larger opening in the middle. If a pump is pumping water at the same rate through both hoses, which one will produce more water in one minute?
• The hose with the larger opening. • Conductors have low ____________. • Insulators have high _____________.
Resistance
• Can be calculated • voltage/current • Voltage is the energy that a power source
gives to the electrons in a circuit
More on Circuits
• Circuits can be in a ________ or __________. • Series circuits have a power supply (battery)
and wire, but they contain multiple electrical devices.
• Example: decorative lights • What happens on some strings when one bulb
blows? • If the entire string of lights stops working, you
have a series circuit.
Parallel Circuits
• Parallel circuits have more than one path for the current to follow.
• Homes are mostly wired this way. • If you have a string of decorative lights, if
one blows, the others will remain lit.
Fuses
• Provide safety for circuits to prevent fires • Fuses have metal on top that melts if it
gets too hot. When it melts, the circuit is broken. What happens when a circuit is broken?
• It stops transporting electricity.
Circuit Breakers
• Are also safety devices to prevent fires • When they get too hot, they switch
themselves off or open the circuit. • What happens when a circuit is open? • It stops working! • Circuit breakers can be reset
Currents
• AC: ___________________________ (the current can flow more than one way)
• DC: ___________________________ (current can only flow one way)
• AC is what we have in our homes. • DC is what batteries offer.
Let’s Review
• Electricity is the flow of electrons • Static electricity is a buildup of electric
charge • The charges can build up by induction,
friction or conduction • Current, the rate of flow of electricity, is
measured in amperes. • A closed circuit is complete & unbroken • An open circuit is incomplete & broken
Review
• Drawings of circuits are called schematics • Resistance measures how easily
electricity flows through a material