IB+MYP+ELECTRICITY

=__Static Electricity__=
 * When an insulator or conductor has static electricity,**
 * it contains an imbalance of positive or negative charges.**


 * Insulator: A material that does not easily allow __ electricity __ to pass through it.**
 * Examples) __ Air, Cloth and Rubber __**


 * Conductor: A material that readily permits the passage of an __ electric current __through it. A material which contains movable __ electric charges __.**
 * Examples) Most of the conductors belong to the class of substances called....................**

What cause a charge?
Consider an atom.
 * If the object is physically rubbed, the __ electrons __ can be transferred from one to the other.**

Make sparks fly with John Travoltage. Wiggle Johnnie's foot and he picks up charges from the carpet. Bring his hand close to the door knob and get rid of the excess charge. media type="custom" key="12862360" Describe and draw models for common static electricity concepts (transfer of charge, attraction, repulsion, and grounding).
 * Simulation:** JohnTravoltage from Phet

**Charges can be __ +ve __ or -ve **

 * **Like charges __ repel __.**
 * +ve and +ve charges __ repel __.**
 * -ve and -ve charges __ repel __.**
 * The same charges, we have got __ repulsion __.**


 * Unlike charges __ attract __.** || [[image:Attract-Repel-Electrostatic-Charges.gif width="98" height="108"]] ||

**Electrostatic Induction**
This is when we __c ause __ a charge to be in a previously uncharged object.

Phet Balloon and Static Electricity media type="custom" key="12041901" Simulation from Phet

1. Draw the diagram what happened to the charged balloon.

__ (balloon, -ve)--> l + _ +_ + + wall __

__ -ve __ charges are repelled from the surface of the wall. __ -ve __ balloon is attracted to +ve on the wall.

2. Draw a charged rod and a piece of paper. Explain why the pieces of paper jiggling around between them.

Static Electricity from the Physics Classroom

=__Electricity__=

How an electric current may exist within a solid material such as a metal wire? How do electrons "flow" through a solid material such as copper? How does //anything// flow through a solid material, for that matter?


 * Mains Electricity**


 * The Electricity we get from a plug is very dangerous. We must NEVER play with this type of electricity. Cells, Batteries and power packs are safe and all of our experiments will use these.

//The battery provides the electrical push (energy) measured in __ volts __. Mr __ Volt __ pushes the electrons around the circuit.//

=**__Circuit__**= An electrical //circuit// is any continuous __ path __ for electrons to flow away from a source of electrical potential (voltage) and back again.

Build circuits from schematic drawings. Use an ammeter and voltmeter to take readings in circuits. Warning: There must be an unbroken path of conductors going from the power supply to the bulb/device and then back to the power supply. media type="custom" key="12862422"
 * Simulation:** Circuit Construction Kit (DC only) from Phet
 * Provide reasoning to explain the measurements and relationships in circuits.
 * Discuss basic electricity relationships in series and parallel circuits.
 * Provide reasoning to explain the measurements in circuits.
 * Type of Circuit || Series || Parallel ||
 * Voltage || Voltage splits || Voltage is the same ||
 * Current || Current is the same || Current splits ||

**//Voltage//**
Electric Potential Difference (Electrical "pressure") between two different terminals. Voltage is the __ energy __ transferred per unit __ charge __ passed. The volt is a __ joule __ per __ coulomb __. Voltage is measured in the unit of the __ //volt// __ (__ V __) 1 volt is equal to 1 joule of energy imparted to 1 coulomb of charge (6.25 ×1018 electrons): W = Work, or potential energy (joules) Q = Charge (coulombs) ||
 * **V=W/Q** || Where, || V = Voltage (volts)

//DC/AC:// //DC// is an acronym meaning //Direct Current//: that is, electrical current that moves in one direction only. //AC// is an acronym meaning //Alternating Current//: that is, electrical current that periodically reverses direction (alternates).

**//Current//**
Electric current (Electricity) is the rate of the __ flow __ of invisible particles called __ electrons __. They go round a track of wire. Current is measured in __ ampere __, the unit of __ amp __ (__ A __). 1 ampere of electric current is the rate of electron motion equal to 1 coulomb per second: Q = Charge in motion (coulombs) t = Time (seconds) ||
 * **I = Q/t** || Where, || I = Electric current (amperes)

The__ brighter __ the bulb, the__ greater __ the current flowing. A usage of current : When an electric .................... flows through wires, it warms them up. Some kinds of wire get so hot that they ..................... One kind of light bulb, called a filament lamp, uses this effect to produce light. They are expensive to run because they give off more ................... than .....................


 * **Measuring**
 * Voltage and Current** || * We always place the ammeter in__ series __ with the component we are testing.
 * We always measure the Voltage in __ parallel __ with the component we are testing. ||
 * **Voltage and Current** || * In a SERIES circuit the __ voltage __ is divided but the __ current __ remains the same. This is why we measure current in series.
 * In PARALLEL circuits the __ current __ is divided but the __ voltage __ remains the same. This is why we measure voltage in parallel. ||

Think of a way to test whether water is a conductor or an insulator. Try your idea out. • Most of the conductors belong to the class of substances called.................... • I think that the hard shiny object that felt cold would .................... electricity, because it is probably made of a .................... • Pure water is an....................However,if there are any impurities in it, such as salt, or chlorine, then the water is a .................... • Air is an .................... which explains why we do not get an electric shock when we stand near a mains electricity socket. • Find out as much as you can about low-energy light bulbs. Explain to your partner why it is a good idea to use these instead of ‘normal’ light bulbs (the ones that get very hot!)
 * Challenge!

//**Resistance**//
Using a tap, we can change the flow of water from fast to slow. With electricity, we change the flow using a resistor. The flow of electron currents can be reduced by adding more resistance to the circuit. Resistance is the __ opposition __ to the electric current. A resistor limits the flow of electricity. The __ bigger __ the resistance, the __ smaller __ the electric current. Resistance is measured in ohm, the unit (Ω) ohm.

Refer to the ppt slide on iLearn: Electricity - Resistance, Power and Energy

//**Explain what Ohm's law is** and find **the properties of resistivity** using the website below;//
 * What are three variables affecting electrical resistance** from tutorvista

media type="custom" key="16993670" width="60" height="60" Electricity from the Physics Classroom
 * Resistance in a wire** from Phet

**Fuses**
Fuses are __s afety __ devices that we use in electricity. If for any reason the __ current __ becomes too high the fuse gets hot and melts. The __ circuit __ is broken and stops working.
 * The fine fibre of steel wool gets hotter than the other wires. In fact, it gets so hot that it melts. Try to find out what temperature steel melts at. Once the fibre melts, there is an air gap in the circuit. No electric current can flow.

A fuse contains a fine metal wire. When the flow of electricity gets too big, this metal gets so hot that it ...................., and breaks. This creates an air .................... in the circuit, which stops the __ flow __ of __ electricity __. This stops the other .................... in the circuit from getting too hot, and causing a fire. || //Watch Voltage, Current and Resistance then, Series and Rarallel Circuits video on iLearn.//


 * Short circuit:** A circuit where the electricity can get from one side of the power supply to the other without going through a electronic device.

**Generating electricity- a summary**
If a …………………… is moved into a coil of wire which is part of a complete circuit, electric…………………….. is produced in the wire.

**4 ways to increase the** amount **of current produced:**
// 1. Move the magnet ………………………… // // 2. …………………….. the number of …………………. // // 3. Use a ………………………. magnet // // 4. Use ………………………. Wire to make the coils //

Electricity can also be generated by rotating a ……………….. of wire in a magnetic ………………...

 * **missing words**: coil, faster, magnet, field, current, thicker, increase, coils, bigger ||

[|Electrical energy game] from www.teachers-direct.co.uk/

= **Household Electricity** = POWER : The amount of electrical energy it converts to other forms of energy in one second. It is measured in Watts(W).



1kWh is the amount of electrical energy consumed by a 1kW appliance in one hour.

**Energy consumed (kWh) = Power (kW) X Time(hours)**
ex) Microwave 2000W used for 30minutes

Power of appliance = 2000W, Time in use 0.5hour

Energy consumed = 2000W X 0.5h = 1000Wh = 1kWh

**Cost of electrical energy = Units of electrical energy used(kWh) X Cost per unit**
ex) 2kW electric iron used for 15minutes. Unit cost is 0.5RMB/kWh

Time in use = 15 min = 0.25h

Energy consumed = 2kW x 0.25h = 500Wh = 0.5kWh

Cost of electricity = 0.5kWh x 0.5RMB/kWh = 0.25 RMB ** Electricity consumption in your household **

V = W/Q, Q = It, P = W/t, W = VQ = VIt and W = Pt thus, P = VI

Example) 3V, 0.4A is written on the packet of torch bulbs. 1. Calculate the power conversion for the bulb in normal use. P = VI = 3V x 0.4A = 1.2 W 2. The life of the bulb is approximately 100 hours. How much energy will it have dissipated in its life time? Energy consumption: E = Pt = 1.2 W x 100 hours = 1.2 W x 360000 s = 432000 J


 * Calculate estimated electricity cost of your household for a month.**

Questions: 1. What are your daily, weekly and monthly electricity consumption?

2. Estimate your electricity cost.

3. What is the biggest electricity consuming device?

4. What is your actual monthly electricity cost?
 * Items || Power of electronic device in watts || Number of device in your house || Daily time estimation using the device in hour || Daily Electricity Consumption in kWh || Weekly E.C. in kWh || Monthly E.C. in kWh || Electricity cost per hour in Shanghai || Monthly Electricity Cost in your household in RMB ||  ||
 * Total ||  ||   ||   ||   ||   ||   ||   ||   ||   ||
 * Total ||  ||   ||   ||   ||   ||   ||   ||   ||   ||
 * Total ||  ||   ||   ||   ||   ||   ||   ||   ||   ||
 * Total ||  ||   ||   ||   ||   ||   ||   ||   ||   ||
 * Total ||  ||   ||   ||   ||   ||   ||   ||   ||   ||
 * Total ||  ||   ||   ||   ||   ||   ||   ||   ||   ||
 * Total ||  ||   ||   ||   ||   ||   ||   ||   ||   ||
 * Total ||  ||   ||   ||   ||   ||   ||   ||   ||   ||
 * Total ||  ||   ||   ||   ||   ||   ||   ||   ||   ||

5. What are your strategies to reduce your electricity consumption?