Electricity and Magnetism

What is Electricity? A form of energy caused by moving electrons. Electricity TedEd

Charge: A buildup or shortage of electrons.  Gaining or losing e-s develops a neg. or pos. charge in an object.  Charges exert forces (push or pull) on each other.  Law of Electric Charges Like (same) charges REPEL Opposite charges ATTRACT

Conductors  A conductor allows ___________/e-s to flow easily  Some conductors are better than others Examples: _______ Iron

Insulators  An insulator _______ electric charges from _________ easily, Examples: RubberCork WoodPlastic

Electric Current  Electric Current is the ______ of electrons/charge through a conductor_________  There are two types of electric current: __________ Current _________ Current

Alternating Current (AC)  Changes __________ at a regular rate.  Most commonly used type of electricity because it does not create as much heat. Examples: Powerplants Houses Christmas lights

Direct Current (DC)  Always flows in one _______.  Always flows from _________ to positive Example: __________  Creates a lot of heat

Resistance  __________ to current flow (anything that ________ down current), mostly a load. Unit of measure is the ohm Measured with an ohmmeter

Higher resistance would mean ______ (higher, lower) heat produced in a circuit. Explain.

What is a circuit?  The path an electric current follows  Consists of four parts: 1.___________:Something to get the power from. Ex. ________, power line. 2. ______: Something that will use the power 3. _______: To _______ the electricity 4. Switch: To open or _____ the circuit, not ________. Current flows only through a closed circuit. Brainpop on circuits Brainpop on circuits

Simple Circuit diagram (copy on left page) cellswitchlampwires Scientists usually draw electric circuits using symbols;

 Give some examples of loads that may be found in your kitchen.

In which of the following circuits will the bulb NOT light up and why?

What is a series circuit?  A circuit where current follows only one _______. Connected _____ to ______.  Diagram:

Series Circuit If one light goes ______, the whole _______ goes out. If more ______ are added all of the bulbs get ________. Uses: Automatic doors Alarms

What is a parallel circuit?  Current follows _____ than one ______. Connected in parallel setup.

Parallel Circuit If one _______goes out, the others __________ on. If more bulbs are _______ all of them will still glow at _____ brightness. Used in: Homes Schools Buildings

 Series or parallel? Draw circuit diagram.

Series or Parallel? Circuit diagram

Series or parallel? Circuit diagram

Series or Parallel? Circuit diagram.

Series or Parallel?

In this setup, is it possible to run the motors without turning on the bulbs? If not, what would you have to change?

05/26Current Electricity Notes IQ: Going down a plastic slide and getting a static charge is an example of conversion from: a. Chemical to mechanical energy b. Nuclear to electrical energy c. Mechanical to light energy d. Mechanical to electrical energy

 Static and Current electricity (8 min) Static and Current electricity (8 min)

Conductors  A conductor allows charges/e-s to flow easily  Some conductors are better than others Examples: Copper Iron

Insulators  An insulator prevents electric charges from flowing easily, Examples: RubberCork WoodPlastic

Charge: A buildup or shortage of electrons.  Gaining or losing e-s develops a neg. or pos. charge in an object.  Charges exert forces (push or pull) on each other.  Law of Electric Charges Like (same) charges REPEL Opposite charges ATTRACT

Current Electricity

Electric Current  Electric Current is the flow of electrons/charge through a conductor. SI unit ampere.  There are two types of electric current: Alternating Current Direct Current

Alternating Current (AC)  Changes direction at a regular rate.  Most commonly used type of electricity because it does not create as much heat Examples: Appliances Houses Christmas lights

Direct Current (DC)  Always flows in one direction.  Always flows from negative to positive Example: Battery  Creates a lot of heat

Voltage  Electrical pressure (pushes current) Atoms that are short electrons and atoms with extra electrons Measured with a voltmeter Unit of measure is the volt

Current  The directed movement of electrons or the flow. (pushed by voltage) Unit of measure is the amp or ampere Measured with an ammeter or amp meter

Resistance  Opposition to current flow (anything that slows down current), mostly a load. Unit of measure is the ohm Measured with an ohmmeter

Higher resistance would mean ______ (higher, lower) heat produced in a circuit. Explain.

What is a Battery?  A series of electrochemical cells  Two types: A wet cell A dry cell

What is a circuit?  The path an electric current follows  Consists of four parts: 1.Source:Something to get the power from. Ex. battery, power line. 2. Load: Something that will use the power 3. Wires: To conduct the electricity 4. Switch: To open or close the circuit, not essential. Current flows only through a closed circuit. Brainpop on circuits Brainpop on circuits

Simple Circuit diagram (copy on left page) cellswitchlampwires Scientists usually draw electric circuits using symbols;

Diagram of a Circuit (copy)

 Copy these circuits on your left hand side page, talk to your partner and explain if they will work. Give reasoning for your answers. Copy these circuits on your left hand side page, talk to your partner and explain if they will work. Give reasoning for your answers.

 Give some examples of loads that may be found in your kitchen.

In which of the following circuits will the bulb NOT light up and why?

5/27 Series and Parallel Circuits IQ: Which of the following is/are NOT required to make a circuit work? a. A source b. Wires c. A magnet d. A load e. A switch

What is a series circuit?  A circuit where current follows only one path. Connected back to back.  Diagram:

Series Circuit If one light goes out, the whole circuit goes out. If more bulbs are added all of the bulbs get dimmer. Uses: Automatic doors Alarms

OQ: Christmas lights are connected in series. What would happen if you pulled one bulb out? Why?

What is a parallel circuit?  Current follows more than one path. Connected in parallel setup.

Parallel Circuit If one light goes out, the others remain on. If more bulbs are added all of them will still glow at full brightness. Used in: Homes Schools Buildings Brainpop

 Series or parallel? Draw circuit diagram.

Series or Parallel? Circuit diagram

Series or parallel? Circuit diagram

Series or Parallel? Circuit diagram.

In this setup, is it possible to run the motors without turning on the bulbs? If not, what would you have to change?

OQ: What role do batteries have in circuits? A.They are the source of potential energy in a circuit. B.They are the source of electrons that moves through the circuit. C.They control how hard it is for the electricity to pass through a circuit. D.They regulate the electrical current by storing then releasing charge.

 OQ: Which is better to use with smoke alarms: a series or parallel circuit and why?

5/23 Circuit Safety  IQ: Draw a circuit diagram with the following: One switch controls the whole circuit. R1 goes out if R2 is broken. R3 stays on if R1 or R2 is broken. R3 also has a switch of its own.

 Water & broken wires can cause a short circuit Current skips load Heats up wire too much Can cause a fire  Too many plugs in an outlet can cause an overload

Circuit Safety 1. Fuses a) Contains thin strip of metal that current flows thru b) If current is too high, metal melts c) Breaks the circuit, so the e - can’t flow d) ‘blowing a fuse’

2. Circuit Breakers a) A switch b) Opens when current gets too high - strip of wire bends away from wires in circuit c) Go to breaker box & reset

OQ: A charge is a buildup or shortage of __________in the atoms of a substance.

5/21 Magnetism Notes  IQ: Which two energy resources do not get their energy from the sun?

Magnetism

Where do magnets come from?  Lodestone is an iron containing mineral that is a natural magnet. Originally found in Magnesia. --MAGNET comes from magnetite (a mineral in rocks)  Iron can be made into magnets.  3 things stick to magnets: iron, nickel, cobalt.  Distance decreases magnetic force.  ed.org/EducationResources/HighSchool/Magnetism/magneticbehavior.htm ed.org/EducationResources/HighSchool/Magnetism/magneticbehavior.htm

Magnetic Poles  A pole is the area of the magnet where the magnetic effect is the strongest.  One pole of the magnet will always point north- north pole. The other pole will point south- south pole.

 Like poles repel.  Unlike poles attract.  ed.org/EducationResources/HighSchool/Magnetism/twoends.htm ed.org/EducationResources/HighSchool/Magnetism/twoends.htm

Magnetic Fields

Magnetic Fields  Exist in regions surrounding magnets.  Strongest at the poles.  Exerts a torque on a compass needle. (Demo)  Compass needles allow us to map out magnetic fields.

 Magnetic field lines flow out from the N to the S pole.  They are continuous and never cross

Magnets have two ends or poles, called north and south poles. At the poles of a magnet, the magnetic field lines are closer together. Unlike poles of magnets attract each other and like poles of magnets repel.

What are magnetic domains? Magnetic substances like iron, cobalt, and nickel are composed of small areas where the groups of atoms are aligned like the poles of a magnet. These regions are called domains. All of the domains of a magnetic substance tend to align themselves in the same direction when placed in a magnetic field. These domains are typically composed of billions of atoms. Magnetic Domains

Making a magnet…  Rubbing a magnetic substance with a permanent magnet in the same direction several times can align all of the domains and the material will act like a magnet.  ed.org/EducationResources/HighSchool/Magnetism/magn eticdomain.htm ed.org/EducationResources/HighSchool/Magnetism/magn eticdomain.htm

2 types of magnets  Temporary magnets only act as magnets either in the presence of an electric current or when near the magnetic field of another magnet. Ex. electromagnets, paper clips stuck to a magnet.  Permanent magnets are stronger and stay magnetized for long periods of time. Ex. fridge magnets, magnets made of alnico.

Losing magnetism Magnets, especially temporary magnets, will lose their domain alignment if dropped, struck too hard, or heated.

The earth is like a giant magnet! The nickel iron core of the earth gives the earth a magnetic field much like a bar magnet.

Earth’s magnetic field

 Maglev Trains Maglev Trains  Brainpop Brainpop

 OQ: What would happen if you cut a bar magnet in half?

Where do magnets come from?  Lodestone is an iron containing mineral that is a natural magnet. Originally found in Magnesia. --MAGNET comes from ________ (a mineral in rocks)  ________ can be made into magnets.  3 things stick to magnets: iron, _______, _____.  Distance ___________ magnetic force.

Magnetic Poles  A pole is the area of the magnet where the _________ _______ is the ___________.  One pole of the magnet will always point _______- north pole. The other pole will point south- __________.

 _____ poles _______.  ________ poles _______.

Magnetic Fields  Exist in _______ surrounding magnets.  _________ at the poles.  Exerts a torque on a compass needle. (Demo)  Compass needles allow us to map out magnetic fields.

Magnetic Field lines  Magnetic _____ lines flow out from the N to the S pole.  They are continuous and never ________.

Magnets have two ends or poles, called north and south poles. At the poles of a magnet, the magnetic field lines are closer together. Unlike poles of magnets attract each other and like poles of magnets repel.

What are magnetic domains? Magnetic substances like iron, cobalt, and nickel are composed of ____ _______ where the groups of _______ are __________ like the poles of a magnet. These regions are called ____________. All of the domains of a magnetic substance tend to align themselves in the same __________ when placed in a magnetic _________. These domains are typically composed of billions of atoms. Magnetic Domains

Making a magnet…  Rubbing a magnetic substance with a _____________ magnet in the same direction several times can align all of the ________ and the material will act like a ________.

2 types of magnets  _________ magnets only act as magnets either in the presence of an ______ _______ or when near the magnetic _____ of another ______. Ex. electromagnets, _______ ______stuck to a magnet.  ___________ magnets are ______ and stay magnetized for long periods of time. Ex. ______ magnets, magnets made of alnico.

Losing magnetism Magnets, especially temporary magnets, will _____ their _______alignment if ______, ______ too hard, or _______.

The earth is like a giant magnet! The nickel iron _________ of the earth gives the earth a magnetic ______much like a _______magnet.

5/17 Magnetism cont’d  IQ: Find the mistakes in the following pics/diagrams:

5/20 Electromagnetism, Motors, Generators notes IQ: Which of the following is NOT necessary to produce electricity in a power plant? a. Mechanical energy b. Chemical energy c. Coil/wire d. Magnets

Electromagnets: Oersted’s Discovery!  The presence of an electric current in a wire causes a torque in a compass nearby.  A ______ carrying wire generates a _________ field- Electromagnetism. 

Electricity & Magnetism  A __________ is a coiled loop of wire which acts like a bar ________ when ________ is passed through it.

A stronger magnetic field can be made by using an ______ core/center.

Electromagnets An electromagnet is a _______ magnet that can be _______ on and ____.

How to increase ______ in an electromagnet: Increase _________ Increase the number of _______ of wire to the solenoid. Wind the coils of a solenoid ___________ together. Use __________ ferromagnetic (iron containing) material for the _______.

Electric Motor  A motor is a device that converts ________ energy into mechanical energy by making a current carrying wire spin inside a magnetic field.  Contains an electromagnet.  Uses: ______, washing machines, etc.

What are electric motors? An electric motor is a device which changes electrical energy into mechanical energy.

Electric generator  A device that converts __________ energy into electrical energy by using a wire inside a changing magnetic ______.  Spinning the coiled wire inside the magnetic field makes electrons move through the wire to light the bulb.

OQ: Which of the following contain/s a motor? A generator? a. A battery. b. A light bulb. c. A wind turbine. d. A bicycle. e. A blender.

 OQ: Compare and contrast a motor and a generator.

Magnetism review  tesize/science/physics/magnetism_ 1.shtml tesize/science/physics/magnetism_ 1.shtml

Diagrams  Source Resistance  LampMotor  Wire  Switch

 OQ: A magnet cannot be used to do which of the following? A. Create mechanical energy B. Create electrical energy C. Extract aluminum out of a recycling bin D. Levitate an object

5/20 Electromagnetism, Motors, Generators notes IQ: Which of the following is NOT necessary to produce electricity in a power plant? a. Mechanical energy b. Chemical energy c. Coil/wire d. Magnets

Electromagnets: Oersted’s Discovery!  The presence of an electric current in a wire causes a torque in a compass nearby.  A current carrying wire generates a magnetic field- Electromagnetism. 

Electricity & Magnetism  A solenoid is a coiled loop of wire which acts like a bar magnet when current is passed through it.

The direction of the current determines the direction of the magnetic field in a current carrying wire.

A stronger magnetic field can be made by using an iron core/center.

Cause All magnetism is caused by the movement of charges.

Electromagnets An electromagnet is a strong magnet that can be turned on and off.

How to increase strength in an electromagnet: Increase current Increase the number of loops of wire to the solenoid. Wind the coils of a solenoid closer together. Use stronger ferromagnetic (iron containing) material for the core. Brainpop

Electric Motor  A motor is a device that converts electrical energy into mechanical energy by making a current carrying wire spin inside a magnetic field.  Uses: fans, washing machines, etc.  simulation simulation

What are electric motors? An electric motor is a device which changes electrical energy into mechanical energy.

Go to the next slide  How does an electric motor work?

Simple as that!!

Electric generator  A device that converts mechanical energy into electrical energy by using a wire inside a changing magnetic field.  Phet simulation Phet simulation  Brainpop Brainpop

We have seen how electricity can produce a magnetic field, but a magnetic field can also produce electricity! How? What is electromagnetic induction? Moving a loop of wire through a magnetic field produces an electric current. This is electromagnetic induction. A generator is used to convert mechanical energy into electrical energy by electromagnetic induction. Carefully study the next diagrams:

OQ: Which of the following contain/s a motor? A generator? a. A battery. b. A light bulb. c. A wind turbine. d. A bicycle. e. A blender.

 OQ: Compare and contrast a motor and a generator.

Magnetism review  tesize/science/physics/magnetism_ 1.shtml tesize/science/physics/magnetism_ 1.shtml

Diagrams  Source Resistance  LampMotor  Wire  Switch

 OQ: A magnet cannot be used to do which of the following? A. Create mechanical energy B. Create electrical energy C. Extract aluminum out of a recycling bin D. Levitate an object

5/29 Current Electricity/Circuits IQ: Identify the following objects as motor, generator, solenoid, electromagnet: