Unit+4+Electricity+and+magnetism+Electrical+quantities

4.2.1 Electric charge • Distinguish between electrical conductors and insulators and give typical examples • Recall and use a simple electron model to distinguish between conductors and insulators

Static Electricity
When an insulator or conductor has static electricity, it contains an imbalance of positive or negative charges.

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

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

**all about circuits**
Core • State that there are positive and negative charges • State that unlike charges attract and that like charges repel • Describe simple experiments to show the production and detection of electrostatic charges • State that charging a body involves the addition or removal of electrons. Supplement • State that charge is measured in coulombs


 * Brainpop**: Electricity, Current electricity,

**What causes a charge?** __ Friction __
Consider an atom.
 * If the object is physically rubbed, the __ electrons __ can be transferred from one to the other. Charges can be __ +positive __ or __ - negative. __**

**[|Electrostatic charges] from thefreedictionary.com (Produced or caused by static electricity):**
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. Answer the the questions below. media type="custom" key="22218262"
 * Simulation:** JohnTravoltage from Phet
 * 1) How does John Travoltage pick up charges? He picks up charges by gaining electrons from the carpet when rubbing his foot against it.
 * 2) What is his charge as he rubs his foot against the carpet? He becomes negatively charged.
 * 3) What is the carpet’s charge? The carpet is positively charged.
 * 4) What happens when John Travoltage touches the metal door knob? The electrons flow through the door knob.
 * 5) What is this term called? Discharge



The same charges__ repel __.
|| ||



Supplement • Give an account of charging by induction • Recall and use the simple electron model to distinguish between conductors and insulators

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

Simulation from Phet Balloon and Static Electricity media type="custom" key="22218268" 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. [|Electrostatics] from BBC Bitesize [|Electrostatics with balloon] Static Electricity from the Physics Classroom Uses of electrostatics = = Supplement • Describe an electric field as a region in which an electric charge experiences a force • State that the direction of an electric field at a point is the direction of the force on a positive charge at that point • Describe simple field patterns, including the field around a point charge and the field around a charged conducting sphere and the field between two parallel plates ( not including end effect )

An electric field is a region of space where a charged object experiences a force due to its charge.
Electric field lines can be used to show the direction and strength of the field. We take the direction of the field that a small +ve charge would accelerate if place in the field.
 * [[image:sciencelanguagegallery/Electric field induced by a positive electric charge.png width="256" height="256"]] ||  || [[image:Electric field induced by a negative electric charge.png width="256" height="256"]] ||
 * [|Electric field line induced by a positive charge] ||  || [|Electric field line induced by a negative charge] ||


 * [|Dipole field]** from http://abyss.uoregon.edu

Electric Field Hockey simulation from Phet
media type="custom" key="22257104"

Field lines due to parallel charged plates. Field between plates is uniform.
Images from [|www.pstcc.edu/]

Electric field lines for two oppositely charged parallel plates are evenly spaced except at the very ends. The field between plates is __u niform __ and the electric field strength is the __ same __ anywhere between the plates. Charged Parallel Plates from http://www.regentsprep.org Watch Paintsprayer. mpg/Electric Fence. mpg Stactic electricity media type="custom" key="29317375" Brainiac - Electric Fence Published on 7 Nov 2006 Clip taken from UK Show, Brainiac, Season 1 Episode 4. =__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?

4.2.2 Current Core • State that current is related to the flow of charge • Use and describe the use of an ammeter, both analogue and digital • State that current in metals is due to a flow of electrons Supplement • Show understanding that a current is a rate of flow of charge and recall and use the equation I = Q/t • Distinguish between the direction of flow of electrons and conventional 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) || Coulomb: a unit of electrical charge equal to the amount of charge transferred by a current of 1 ampere in 1 second. The__ brighter __ the bulb, the__ greater __ the current flowing.
 * //Current//**
 * **I = Q/t** || Where, || I = Electric current (amperes)

A usage of current : When electric charges flow through wires, it produces heat. Some kinds of wire get so hot that they emit ..................... 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 ................... energy than ..................... energy.
 * Do you remember this!!!**


 * **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. ||
 * Complete questions on Combination circuits from www.physicsclassroom.com**


 * Challenge!

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!)

4.2.5 Resistance Core =__Homework reading!__= //**Explain what Ohm's law is** and find **the properties of resistivity**.//
 * State that resistance = p.d./current and understand qualitatively how changes in p.d. or resistance affect current
 * Recall and use the equation R = V/I
 * Describe an experiment to determine resistance using a voltmeter and an ammeter
 * Relate (without calculation) the resistance of a wire to its length and to its diameter

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

The unit is named after German physicist // Georg Simon Ohm //. The Ohm’s law states that the electrical charges flowing through an electrical element(a resistance) between two points on the element( the resistor) is directly **__ proportional __** to the __ potential **difference** __ (voltage) across those points. **The unit ohm can be defined as the resistance offered by an element when a voltage of 1 volts applied to the element produces a current of 1 ampere in the element.**
 * What are three variables affecting electrical resistance** from tutorvista

**Investigation project on Ohm's Law**
Support material for Physics investigation lab report To construct a Voltage against Current graph to analyze the resistance of an unknown resistor using a variable resistor (rheostat). Ohm's law [|resistance] from BBC Bitesize [|Ohm's Law] from ftp://ftp.pasco.com
 * Aim: To find out the resistance of an unknown resistor using Ohm's law.**
 * Introduction/Background information :**
 * Hypothesis:**


 * Variables:**
 * || What is it? Name it. || Methods of management or measurement. ||
 * Independent varialble (unit) ||  ||   ||
 * Dependent variable (unit) ||  ||   ||
 * Controlled variable 1 ||  ||   ||
 * Controlled variable 2 ||  ||   ||
 * Controlled variable 3 ||  ||   ||
 * Apparatus/Material:**


 * Diagram:**

1) Construct your circuit the same as the diagram above. 2) With the rheostat placed to the far RIGHT, take readings of both current (Ammeter) and potential difference (Voltmeter) across the unknown resistor. ( In IB DP Physics, ensure you add uncertainties in your readings.) 3) Slide the rheostat a small distance to the right and repeat step 2. Repeat this process until you have **AT LEAST 6** different readings for both potential difference and current. 4) Make a graph of potential difference (y-axis) against current (x-axis). 5) Draw a line of best fit through your graph ensuring it passes through the origin.
 * Method:** Numbered step [|measuring resistance] using voltmeter and ammeter

//**Challenges! **// 1. Explain why do we need to ensure the line of best fit passing through the origin. 2. Draw error bars for all data points. 3. Do the same experiment using a filament lamp and find the resistance of it.



Raw data table Processed data table (You need to prepare some values to plot a graph. Think of what values you need to plot.) Sample calculation ( i.e. one example of each calculation you used in your processed data table)
 * Results:** (mA means milliamp……..1000 mA = 1 A)
 * Voltage (V) || Current (A) || Voltage (V) || Current (A) || Observations ||
 * Trial 1 || Trial 1 || Trial 2 || Trial 2 || Brightness / Colour / Change in Temperature / Change in shape / Smell / etc. ||
 * Average || Percentage || Any calculated data || Etc. ||


 * __Graph__ //( V against I graph )//**
 * 1) Plot V against I graph. Add the line of best fit.
 * 2) Calculate the gradient if the line of best fit is showing a linear relationship and find the value of your resistance. ([|Gradient and resistance] a warning from www.furryelephant.com)
 * 3) Calculate an ‘average’ resistance of your resistor and compare it to your graphical answer.

//**Some questions to consider !**// 1. Describe what happens to **//V//** when **//I//** increases. 2. Describe the value of **//R.//** Are there any change in **//R//** as **//I//** increases? 3. Describe and explain if your resistance is Ohmic or Non-ohmic (To answer this, you will need to read a lot about Ohm’s law). 4. Identify possible causes of uncertainty, in data or in a conclusion
 * __ Discussion: __**

1. Were your graphical and calculated results the same? What could have caused any differences? 2. Is your experiment valid? 3. Is your procedure reliable? 4. Identifies strengths of the investigation. 5. Discuss how the weakness/limitation might have impacted the results and think of any improvements you can suggest in your methods if you do the experiment again. 6. Think of any investigations you would like to do further. (i.e. Finding a resistance using other devices such as a filament bulb.)
 * __ Evaluation: __** Improvements to be made.

1. Restate your results. Were they what you expected? 2. Describe whether your hypothesis is supported or not?
 * __ Conclusion: __**

Don't forget to include Bibliography! ([|MLA] format)
 * __Bibliography:__**

In report writing,
 * Use specific scientific notation and terminology but, otherwise, use simple sentence structure and language to express your ideas.
 * Include evidence supporting your ideas.
 * Do not start your discussion/analysis/evaluation/conclusion with ‘I’. Start with one of the following suggesstions. ( this result, this data, the method used in this investigation, the limination, it,... )
 * Human error occurs all the time and it is one of the biggest sources so indicate what you’ve done to reduce the error but do not use it as an evaluation as it is random error which means it is hard to improve or control. Focus your evaluation on ‘systemic errors’ as it is easier to improve and find a solution.
 * Give specific examples of interpretations and applications.
 * Make sure to include if your investigation is valid and reliable and explain the reasons why.

Further information you can consider including in a Physics investigation report taken from IGCSE 0625 Syllabus

Homework: Complete Ohm's law lab report (Due on MB: 22nd September 2017) Bring your printed lab report on 29th September 2017 for peer editing. AIS YEAR 11 IGCSE 0625 PHYSICS Compare your graph with the sample report below.

Supplement • Sketch and explain the current-voltage characteristic of an ohmic resistor and a filament lamp Ohm's law investigation if a filament lamp is Ohmic or non-Ohmic.(Thank to Mihn Tri for sharing the original copy of this lab report.)

Supplement • Recall and use quantitatively the proportionality between resistance and length, and the inverse proportionality between resistance and cross-sectional area of a wire media type="custom" key="22218288" width="80" height="80" Answer to the questions below. Electricity from the Physics Classroom Watch resistance.flv
 * [|Resistance in a wire]** from Phet
 * 1) What variables affect the resistance in the wire?
 * 2) What must happen for the wire’s resistance to be at its greatest?
 * 3) What must happen for the wire’s resistance to be at its least?




 * Fuses**

Fuses are __s afety __ devices that we use in electricity. Fuses are included in circuits to stop excess currents from flowing. If for any reason the __ current __ becomes too high the fuse gets hot and melts. The __ circuit __ is broken and stops working. The current rating of the fuse should be just above the value of the current that flows when the appliance is operating normally. Read the worked example 3 on your text page 213.
 * 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.

1. What is the difference between direct current (d.c.) and alternating current (a.c.).

2. a) Why do we have a fuse in an appliance or a plug?

b) How does a fuse work?

3. This question 3 is about an oven. a) If the normal working current of the oven is 9A. What size fuse should be fitted?

b) If a fault occurs and a current of 15A flows, explain how the fuse would protect the appliance from overheating and causing a fire.

c) What is the advantage of having a circuit breaker rather than a fuse to protect an appliance?

4.2.3 Electro-motive force Core • State that the e.m.f. of a source of electrical energy is measured in volts Supplement • Show understanding that e.m.f. is defined in terms of energy supplied by a source in driving charge round a complete circuit

The volt is defined as the __ energy __ transfer per __c oulomb __ of charge as charges move between two points in a circuit. i.e. energy change per unit charge (so that 1 V = 1 J C-1) Introduce the terminology of electromotive force (voltage across a source of electrical energy) and potential difference (voltage across a component that uses electrical energy). Despite its name, emf is not a force but a __ volta __g__ e __, measured in volts. from[| Teaching Advanced Physics Episode 105]
 * V = ΔW / ΔQ**

4.2.4 Potential difference • State that the potential difference(p.d.) across a circuit component is measured in volts • Use and describe the use of a voltmeter, both analogue and digital

The electricity which comes into your house through the wall sockets is called Mains Electricity. It is different from the electricity which comes from cells in two important ways. 1. I t is alternating current (a.c.) 2. It is at a much higher voltage.
 * [|Mains Electricity] from BBC Bitesize**

Mains electricity in the UK is supplied at 240 Volts, China is at 230 Volts, Vietnam is 220 Volts and 110 Volts in the USA. //The battery provides the electrical push (energy per charge) measured in __ volts __. Mr __ Volt __ pushes the electrons around the circuit.//
 * 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.

Supplement • State that charge is measured in coulombs • Recall that 1V is equivalent to 1 J/C


 * //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) || Coulomb: a unit of electrical charge equal to the amount of charge transferred by a current of 1 ampere in 1 second.
 * **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).

Watch potential difference.flv

4.2.6 Electrical energy Core • Understand that electric circuits transfer energy from the battery or power source to the circuit components then into the surroundings Supplement • Recall and use the equations P=IV and E=IVt

**Power**


Power is the rate at which energy is transferred or transformed.
 * **Power (W)** || = || Energy transformed (J) / time taken (s) ||
 * 1 **W** || = || 1 **J / s** ||
 * __The rate of at which energy is transferred in the circuit__ depends on both the**__ e.m.f. __ **//V// of the supply and the** __ current __ **//I// that it pushes round the circuit.**
 * Power (W) = current (A) X potential difference (V)**
 * P = VI**
 * P = E/t, E = Pt, E = VIt**

Homework: Do questions on page from 194 to 196.

Remember the equations and the units below. ** Electricity consumption in your household **
 * Equation ||  || Unit ||
 * **E = VIt** ||  ||   ||
 * **P = E/t** ||  ||   ||
 * **P = VI** ||  ||   ||
 * **V = IR** ||  ||   ||
 * **P = I** 2 **R** ||  ||   ||
 * **V = W/Q = E/Q** ||  ||   ||
 * **Q = IT** ||  ||   ||
 * **E = VIT** ||  ||   ||

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?

4.3.1 Circuit diagrams Core • Draw and interpret circuit diagrams containing sources, switches, resistors (fixed and variable), heaters, thermistors, light-dependent resistors, lamps, ammeters, voltmeters, galvanometers, magnetising coils, transformers, bells, fuses and relays Supplement • Draw and interpret circuit diagrams containing diodes Refer to your text page 198, 207

=**__Circuit__**= [|Standard electrical circuit symbols] from BBC Bitesize [|Try out the quiz on circuit symbols] from www.sporcle.com An electrical //circuit// is any continuous __ path __ for electrons to flow away from a source of electrical potential (voltage) and back again.

4.3.2 Series and parallel circuits Core Supplement
 * Understand that the current at every point in a series circuit is the same
 * Give the combined resistance of two or more resistors in series
 * State that, for a parallel circuit, the current from the source is larger than the current in each branch
 * State that the combined resistance of two resistors in parallel is less than that of either resistor by itself
 * State the advantages of connecting lamps in parallel in a lighting circuit
 * Calculate the combined e.m.f. of several sources in series
 * Recall and use the fact that the sum of the p.d.s across the components in a series circuit is equal to the total p.d. across the supply
 * Recall and use the fact that the current from the source is the sum of the currents in the separate branches of a parallel circuit
 * Calculate the effective resistance of two resistors in parallel

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="22218286"
 * 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.

Task: You have an unlimited number of wires and two types of resistors, 1 ohm and 2 ohms. You are required to construct circuit that has a total resistance of 3.14159 ohms?
 * Type of Circuit || Series || Parallel ||
 * Voltage || Voltage splits || Voltage is the same ||
 * Current || Current is the same || Current splits ||

4.3.3 Action and use of circuit components Core
 * Describe the action of a variable potential divider (potentiometer)
 * == V 2 out = [ R 2 / (R 1 +R 2 ) ] V ==

[[image:Potentiometer.jpg width="245" height="145"]]
|| ==V IN = V 1 + V 2 out ==

V 2 out = [ R 2 / (R 1 +R 2 ) ] V IN
|| Image from www.webanswers.com Potential dividers divide up the voltage within a circuit, so that parts of a circuit only receive the voltage they require. Potential dividers usually consist of two or more resistors arranged in series across a power supply. [|Potential divider] from BBC Bitesize

How [|fire alarm](circuiteasy.com/fire-alarm) works? Image from text p.208 How a lamp switched on in the dark automatically? Image from your text p 208. [|Thermistors and LDRs] from BBC Bitesize [|Thermistors and LDRs] from schoolphysics.co.uk
 * Potentiometer**: A variable resistor with a third adjustable terminal. The potential at the third terminal can be adjusted to give any fraction of the potential across the ends of the resistor.
 * Describe the action of thermistors and light- dependent resistors and show understanding of their use as input transducers
 * Thermistor: ** An electrical device whose resistance __ decrease __ as its temperature increases
 * LDR: Light Dependent Resistors**
 * Describe the action of a relay and show understanding of its use in switching circuits
 * Relay:** Type of switch, typically incorporating an electromagnet, that is activated by a current or signal in one circuit to open or close another circuit.
 * [[image:RELAY COIL.PNG width="353" height="222"]] || [[image:RELAY.PNG]]

Image above from [|BBC GCSE Bitesize] Image left from <span style="background-image: url(">[|itp.nyu.edu]

A ** relay ** is a switch that’s controlled by a small electric current. Relays take advantage of the fact that when you pass an electric current through a wire, a magnetic field is generated surrounding the wire as well. This is called ** induction **. ||

<span style="background-color: #ffffff; color: #222222; font-family: arial,sans-serif; font-size: small;">**Transducer:** a device that converts variations in a physical quantity, such as pressure or brightness, into an electrical signal. A transducer converts a signal in one form of energy to a signal in another. Examples) Thermistor, LDR(Light Dependent Resistors), Potentiometers(They convert the change in displacement into change in the resistance, which can be measured easily.), Bridge circuits( (These convert the physical quantity to be measured into the voltage.), Wheatstone bridge (It converts the displacement produced by the physical quantity to the current in the circuit.)

Supplement [|​Diode] from BBC Bitesize [|LED] (Light emitting Diode) from BBC Bitesize
 * Describe the action of a diode and show understanding of its use as a rectifier
 * Diode:** ​A semiconductor device with two terminals, typically allowing the flow of current in one __ direction __ only.

<span style="background-color: #ffffff; color: #222222; font-family: arial,sans-serif; font-size: 16px;">A **<span style="background-color: #ffffff; color: #222222; font-family: arial,sans-serif; font-size: 16px;">transistor **<span style="background-color: #ffffff; color: #222222; font-family: arial,sans-serif; font-size: 16px;"> is a semiconductor device used to __amplify or switch__ electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals for connection to an external circuit. Transistor switching circuit from BBC Bitesize
 * Describe the action of a transistor as an electrically operated switch and show understanding of its use in switching circuits
 * Transistor: **​ Components which do not conduct electricity unless they are turned on by __different__ electrical current. It can act as an amplifier as a transistor can control its output in proportion to the input signal. Alternatively, the transistor can be used as a __ switch __ to turn current on or off in a circuit.

How does a Transistor work? Let's watch and figure it out! media type="youtube" key="IcrBqCFLHIY" width="560" height="315" Published on 9 Jul 2013 by Veritasium

[| Light sensitive switches and temperature operated alarms by Desaqila ramlee] Prezi [|Transistor, LDR operating as light sensitive switches to turn on a LED in a circuit] from educypedia
 * Recognise and show understanding of circuits operating as light sensitive switches and temperature-operated alarms (to include the use of a relay)

<span style="background-image: url(">[|Capacitors] from www.technologystudent.com <span style="background-image: url(">[|Capacitors] from BBC Bitesize <span style="background-image: url(">[|A capacitor] by Adam Britton 4.4 Digital electronics Supplement The difference between a digital signal and an analogue signal; [|Digital and analogue signals] from BBC Bite size What could they look like graphically? Transistor in a circuit from text p.208 <span style="background-color: #ffffff; color: #333333; font-family: verdana,helvetica,arial,sans-serif; font-size: 12.6464px;">Logic gates are digital electronic devices that allow an electronic system to make a decision based on a number on its inputs. <span style="background-color: #ffffff; color: #333333; font-family: verdana,helvetica,arial,sans-serif; font-size: 12.6464px;">Each logic gate (NOT, AND, NAND, OR, NOR etc) acts in a different way, and the action of any logic gate is shown by a Truth Table.
 * Describe the action of a capacitor as an energy store and show understanding of its use in time- delay circuits - Removed 2017/2018 ~
 * Capacitor**: A device used to__ store __ an electric charge, consisting of one or more pairs of conductors separated by an insulator.
 * Explain and use the terms analogue and digital in terms of continuous variation and high/low states
 * Digital signal:** A signal which can be represented as a series of 1s and 0s. It can be perfectly copied.
 * Analogue signal:** A continuously varying signal. It degrades as it is copied.
 * Digital signals || Analogue signals ||
 * State that logic gates are circuits containing transistors and other components
 * State that logic gates are circuits containing transistors and other components
 * Describe the action of NOT, AND, OR, NAND and NOR gates
 * Recall and use the symbols for logic gates
 * Design and understand simple digital circuits combining several logic gates
 * Use truth tables to describe the action of individual gates and simple combinations of gates

<span class="wiki_link_ext">[|Logic gates] and [|the symbols] from BBC Bitesize

IGCSE Electric Circuits Revision notes by physicsatweb.com

PRACTICE <span style="font-family: Arial,sans-serif; font-size: 10pt;">1) What do we call signals where only an on or off option is possible? <span style="display: block; font-family: Arial,sans-serif; font-size: 10pt; text-align: justify;">2) The device used for rectification <span style="display: block; font-family: Arial,sans-serif; font-size: 10pt; text-align: justify;">3) Changing a ac signal to a dc signal <span style="display: block; font-family: Arial,sans-serif; font-size: 10pt; text-align: justify;">4) Gates which give a high output if neither inputs are high <span style="display: block; font-family: Arial,sans-serif; font-size: 10pt; text-align: justify;">5) Gates which give a high output if either input is high <span style="display: block; font-family: Arial,sans-serif; font-size: 10pt; text-align: justify;">6) The number of leads on a transistor <span style="display: block; font-family: Arial,sans-serif; font-size: 10pt; text-align: justify;">7) An electronic switch or amplifier <span style="display: block; font-family: Arial,sans-serif; font-size: 10pt; text-align: justify;">8) A device for storing charge <span style="display: block; font-family: Arial,sans-serif; font-size: 10pt; text-align: justify;">9) Gates which give a high output if both inputs are high <span style="display: block; font-family: Arial,sans-serif; font-size: 10pt; text-align: justify;">10) A temperature dependent input device <span style="display: block; font-family: Arial,sans-serif; font-size: 10pt; text-align: justify;">11) An analogue to digital converter <span style="display: block; font-family: Arial,sans-serif; font-size: 10pt; text-align: justify;">12) A device which converts analogue signals such as sound into a digital signal <span style="display: block; font-family: Arial,sans-serif; font-size: 10pt; text-align: justify;">13) What do we call signals that can have a range of values? media type="youtube" key="UCbhu5zaqqY" width="560" height="315" Logic Gates 04: NAND, NOR, XOR and XNOR Published on 1 Apr 2011
 * 1) Digital || 2) Diode || 3) Rectification || 4) NAND || 5) Or || 6) Three || 7) Transistor || 8) Capacitor || 9) And || 10) Thermistor || 11) Logic gate || 12) Transducer || 13) Analogue ||

4.5 Dangers of electricity Core [|Dangers of electricity] from physicsatweb.com
 * state the hazards of
 * – damaged insulation
 * – overheating of cables
 * – damp conditions

[|Fuses and circuit breakers] from BBC Bitesize
 * State that a fuse protects a circuit
 * Explain the use of fuses and circuit-breakers and choose appropriate fuse ratings and circuit-breaker settings

• Explain the benefits of earthing metal cases <span style="font-family: Andika,sans-serif; font-size: 16px;">Electrical current finds the easiest path to go through so electricity flows down to earth instead, in case there is huge resistance, such as you in the circuit. Earth wire effectively bypass the current (short-circuit) to the ground and not damaging anybody or device. <span style="font-family: Andika,sans-serif; font-size: 16px; line-height: 0px; overflow: hidden;">

<span style="background-image: url(">[|Image from][|www.edexcel-cie.com]

Article taken from [|Electrical safety] from BBC BITESIZE You would get an electric shock if the live wire inside an appliance, such as a cooker, came loose and touched the metal casing. However, the earth terminal is connected to the metal casing so that the [|current] goes through the earth wire instead of causing an electric shock. A strong current surges through the earth wire because it has a very low [|resistance]. This breaks the [|fuse] and disconnects the appliance. = = =Double insulation= Some appliances - such as vacuum cleaners and electric drills - do not have an earth wire. This is because they have plastic casings, or they have been designed so that the live wire cannot touch the casing. As a result, the casing cannot give an electric shock, even if the wires inside become loose. These appliances have double insulation. Symbol for double insulation

hải sơn, Kim Hyeonjun Huynh Vinh Phong || MIKA HOSOI, Duy Anh, SUNMINJUNG, Le The Dan, Dang Thanh Vu || DUONG HANH TRANG, James Do Price Taylor, Nguyen Tran Le, Tran Thanh Huy || Quynh Nhu, Le Nam Trieu (Jack), Thaya Chevaphatrakul, chang seop lim || tomoho kagami, Sota Kawasaki, Vo Quynh Quoc Thang, Andrew Tran Quoc ANh ||
 * Banana || Pineapple || Watermelon || Papaya || Goconut ||
 * Le Hoang Duy Uyen,