Electricity and Magnetism

Electricity and Magnetism

1. Circuits and Parallel

   • Circuits
     • How can we model electrical circuits?
       • In this model Riders = flow of charge Pizza is the electrical energy travelling in the circuit Pizza shop? House party?
     • What is an electrical circuit?
       • An electrical circuit is the path for electrical charge to flow.
       • Needs: energy, a complete loop, components
     • What are conductors and insulators?
       • A conductor allows the flow of  electrical charge
       • An insulator doesn’t allow the  flow of electrical charge
     • How do metals conduct electricity?
       • Free or “delocalized” electrons allow current to flow in an electrical circuit
   • Parallel
     • Diagrams of parallel circuits
     • The components are connected side by side.
       • The current has a choice of routes.
       • If one bulb ‘blows’ there is still be a complete circuit to the other bulb so it stays alight.

2. Static Electricity

   • Static electricity is caused by friction and the movement of negative charges called electrons
   • When two insulating materials rub together, electrons are scraped off one material onto the other one.
   • The object that GAINS the ELECTRONS becomes NEGATIVELY CHARGED.
     • The object that LOSES the ELECTRONS becomes POSITIVELY CHARGED.
   • Only the negative charges (electrons) are able to move
   • Alike charges
     • Two things with the SAME charge REPEL each other.
   • Different Charges
     • Two things with DIFFERENT charges ATTRACT each other.

3. Circuit Parts/Symbols

   • Symbols

4. Current and Ammeter

   • Current
     • What is an electric current?
       • An electric current is a flow of microscopic particles called electrons flowing through wires and components.
         • The current goes in a direction from the Negative terminal to the Positive terminal of a cell.
     • What is an ammeter?
       • An ammeter is a measuring instrument used to measure the current in a circuit. Electric currents are measured in amperes, hence the name. The ammeter is usually connected in series with the circuit in which the current is to be measured.

5. Voltage and Voltmeter

   • Voltage
     • Voltage is the "push" that forces the electricity around
   • Voltmeter
     • Voltage is measured with a voltmeter

6. Power

   • Calculating Power
     • In physics power (P) is measured in watts (W). To work out the wattage of an electrical appliance you need to know how much voltage it uses and how many amps are running through it.
     • The triangle to the right is an equation triangle. This is a great tool for changing equations so that they work out different things in the equation. If the two parts are over one another then you divide and if they are next to each other you multiply.

7. Electromagnets

   • Any wire that has a current flowing through it, also has a very tiny MAGNETIC FIELD around it.
   • When we turn the current off, the magnetic field disappears. This is the basis for a simple ELECTROMAGNET
   • When we turn the current off, the magnetic field disappears. This is the basis for a simple ELECTROMAGNET
   • Making the Magnetic Field Stronger
     • -COIL the wire, so there is more wire in a certain area.
     • -Add a CORE of IRON.
     • -Increase the CURRENT
   • The magnetic effect can be controlled by the flick of a switch.
   • ELECTROMAGNETS are used in lots of different ways; scrap yards, door locks, bells and circuit breakers.

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