Electricity, Magnetism and Electromagnetism PDF

**ELECTRICITY,** MAGNETISM AND **ELECTROMAGNETISM**. **ATOMS\...** \* Have neutrons, protons, and electrons. \* Protons are positively charged \* Electrons are negatively charged **ELECTRONS\...** \* Are located on the outer edges of atoms\...they can be moved. \* A concentration of electron...

**ELECTRICITY,** MAGNETISM AND **ELECTROMAGNETISM**. **ATOMS\...** \* Have neutrons, protons, and electrons. \* Protons are positively charged \* Electrons are negatively charged **ELECTRONS\...** \* Are located on the outer edges of atoms\...they can be moved. \* A concentration of electrons in an atom creates a net negative charge. If electrons are stripped away, the atom becomes positively charged. **THE WORLD IS FILLED WITH ELECTRICAL CHARGES**: **+** **+** **+** **+** **+** **+** **+** ++ STATIC **ELECTRICITY** \* The build up of an electric charge on the surface of an object. × The charge builds up but does not flow. \* Static electricity is potential energy. It does not move. It is stored. **STATIC DISCHARGE**.. \* Occurs when there is a loss of static electricity due to three possible things: \> Friction **-** rubbing ×Conduction - direct contact × Induction -- through an electrical field (not direct contact) Opposite charges attract \+ Like charges repel **ELECTRICITY THAT MOVES\...** × Current: The flow of electrons from one place to another. \* Measured in amperes (amps) \* Kinetic energy **HOW** CAN **WE CONTROL CURRENTS?** × With circuits. × [Circuit:] is a path for the flow of electrons. We use wires. What is the difference between *static* electricity and current electricity? Static electricity is stationary or collects on the surface of an object, whereas current electricity is flowing very rapidly through a conductor. The flow of electricity in current electricity has electrical pressure or voltage. Electric charges flow from an area of high voltage to an area of low voltage. Water flow **Charge** flow High pressure Low pressure High voltage Low voltage BA voltage difference causes **charge** to flow. A A pressure difference causes water to flow. Water pressure and voltage behave in similar ways. **THERE** ARE **2 TYPES OF CURRENTS:** \* Direct Current (DC) - Where electrons flow in the same direction in a wire. **THERE** ARE **2 TYPES OF CURRENTS:** \* Alternating Current (AC) - electrons flow in different directions in a wire **THERE ARE 2 TYPES OF CIRCUITS:** \> Series Circuit: the components are lined up along one path. If the circuit is broken, all components turn off. **SERIES** CIRCUIT C D **THERE** ARE **2 TYPES OF CIRCUITS:** \* Parallel Circuit **-** there are several branching paths to the components. If the circuit is broken at any one branch, only the components on that branch will turn off. PARALLEL **CIRCUIT** **CONDUCTORS** VS. INSULATORS \* Conductors - material through which electric current flows easily. \* Insulators - materials through which \- electric current cannot move. **EXAMPLES** \* Conductors: \* Insulators: +Metal +Water +Rubber +Plastic +Paper **WHAT** IS **RESISTANCE?** \* The opposition to the flow of an electric current, producing heat. \* The greater the resistance, the less current gets through. \* Good conductors have low resistance. \* Measured in ohms. **WHAT** IS **VOLTAGE?** **26** \* The measure of energy given to the charge flowing in a circuit. \* The greater the voltage, the greater the force or \"pressure\" that drives the charge through the circuit. **OHM\'S LAW** \* Resistance = Voltage / Current \* Ohms = Volts / Amps **V=IR I=V/R R=V/**I **MAGNETISM** **What is** magnetism**?** Magnetism is the properties and interactions of magnets The earliest magnets were found naturally in the mineral *magnetite* which is abundant the rock-type *lodestone*. These magnets were used by the ancient peoples as compasses to guide sailing vessels. Magnets produce magnetic forces and have magnetic field lines S 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. North geographic pole 5 N South geographic pole MAGNETS \* USUALLY MADE OF IRON **×** EVERY MAGNET HAS A NORTH AND SOUTH POLES × LIKE SIMILAR CHARGES REPEL \* OPPOSITES ATTRACT **FERROMAGNETIC** \* OBJECTS THAT CAN BE MAGNETIZED (IRON, COBALT, NICKEL) \* 3 TYPES OF MAGNETS × LODESTONE - NATURAL (PERMANENT) × ARTIFICAL INDUCED \* ELECTROMAGNET - temporary magnets produced by moving electric current **C** Lodestone (Natural Magnet) Artificial Permanent Magnet TYPES OF MAGNETS Electromagnet Ferromagnetic material such as iron attracts magnetic lines of induction, whereas nonmagnetic material such as copper does not. Iron Copper Demonstration of magnetic lines of force with iron filings \* NORTH & × SOUTH POLES IU \* If a single magnet is broken into smaller and smaller pieces, baby magnets result SNAP**!** N H Lines Of Magnetic Force CURRENT-CARRYING **WIRE** \* A moving charge creates a magnetic field x \* When a charged particle is in motion - a magnetic force field perpendicular to the motion is created \***ELECTROMAGNETISM** **ELECTROMAGNETISM** \* A MOVING CHARGE CREATES A MAGNETIC FIELD RT HAND **RULE** RFE DIRECTION OF MAGNETIC FIELD Current Wire DIRECTION OF MAGNETIC FIELD \* Current flow direction of thumb \* Magnetic filed - fingers **ELECTROMAGNET IS CREATED BY:** \* SOLENOID: Current flowing through coil of wire Putting a magnet in the middle of the coil of wire increases the strength of the electromagnet\'s magnetic field SOLENOID × A coil of wire is a helix \* Supplied with current it is a solenoid × Add an iron core - simple form of ELECTROMAGNET What is an electromagnet**?** When an electric current is passed through a coil of wire wrapped around a metal core, a very strong magnetic field is produced. This is called an electromagnet. N Electron flow N Electron flow An iron core inserted into the coil becomes a magnet. S **HOW ELECTRIC & MAGNETIC FIELDS** **INTERACT** Faraday **discovered** that the magnetic lines **of force** and **the wire must** have **a motion** relative **to** each **other to induce** an electrical **current** **ELECTROMAGNET INDUCTION** \* Moving a wire through a magnetic field will induce a current (Faraday) × Wire or field can move \* Moving a magnet through a coil of wire will induce an electrical current \"**FARADAY\'S LAWS; OR HOW TO INCREASE THE** STRENGTH OF THE **INDUCED** CURRENT \* Increase the Strength of field or size of magnet \* Increase the SPEED of motion × Change the ANGLE (more perpendicular) Increase the Number of Turns of coil **ELECTROMAGNET INDUCTION** **\*** MOVING A BAR MAGNET THROUGH A COIL OF WIRE WILL INDUCE A CURRENT TO FLOW THROUGH THAT WIRE ELECTROMAGNETIC **INDUCTION** **What are** electric **motors?** An electric motor is a device which changes electrical energy into mechanical energy. Permanent magnet N Electron flow 5 Electromagnet A basic electric motor has a power supply, a permanent magnet, and an electromagnet that can rotate. Power Source How does an electric motor work? Battery Permanent magnet N Brushes N Battery Coil Direction of electron flow Permanent magnet SN Brushes Coil AA battery causes an electric current to flow through the coil of the electromagnet. B Unlike poles of the two magnets attract each other, and the like poles repel. This causes the coil to rotate until the opposite poles are next to **each** other. THE **PRINCIPLE OF THE ELECTRIC MOTOR** Rotating magnets in disk (rotor) **SN** **NS** **NS** repel ANS Stationary magnet SN **SN** attract **NS** **C** UNS B SN **NS** repel A BSN NS **SN** GNS attract **GENERATORS** \* **A generator** is **a device** that **uses induction to** **convert mechanical energy into electrical energy**. Permanent magnets **SN** S **SNA** electric Current **NS** **NS** electric Current A B BSN **S** N NS CNS **N** **SC** C **SN** **ONS** Coil of wire **NS** **NS** Rotating disk **+** **+** TRANSFORMERS A transformer is a device used to change the voltage in a circuit. AC currents must be used. Primary circuit Secondary circuit Vp N N V1 75,000 V in the power lines Magnetic flux concentrated in iron core *p* = primary s = secondary 120 V in your house \* Transformers are extremely useful because they efficiently change voltage and current, while providing the same total power. × The transformer uses electromagnetic induction, similar to a generator. **Transformer** Input (primary) 13,800 volts 1 amp 13,800 watts 120 volts 115 amps Output (secondary) 13,800 watts THANK YOU