11.1 current electricity electrochemical cells (the energy...

11.1 CURRENT ELECTRICITYDefine: CIRCUIT: path that electrons follow. CURRENT ELECTRICITY: continuous flow of electrons in a circuitLOAD: device that converts electrical energy to another form of energySWITCH: a device that turns the circuit on or off by closing or opening the circuit. When the switch is closed, the circuit is complete and allows electrons to flow. An open switch means there is a break in the path so electrons cannot flow.

Electrochemical Cells (the energy source) pg. 434

Define:ELECTROCHEMICAL CELL: package of chemicals that converts chemical energy into electrical energy that is stored in charged particlesBATTERY: combination of electrochemical cells

Wet Cell • 2 pieces of metal placed in liquid• the metal plates (usually zinc and copper) are

called electrodes • the liquid in the cell that conducts the electric

current is called the electrolyte• electrons collect on zinc plate making it

negatively charged and therefore the negative terminal

• Positive charges collect on copper plate making it positively charged and therefore the positive terminal

Dry Cell•Electrolyte is a moist paste rather than a liquid (like in your typical batteries)

Which direction do electrons travel in wet and dry cells? from negative to positive

Date: SNC1D: Electricity

Zinc

Dry Cell

Wet Cell

NegativeTerminal

PositiveTerminal

Potential Difference pg. 437

Define:POTENTIAL ENERGY: energy stored in an object, each electric charge has electrical potential energyQuestion: Would an apple that is held from 10 m have more or less potential energy than an apple dropped from 7 m? Why? the apply dropped from 10m because it is dropped from a higher height

•a battery has potential energy stored in the electrolyte in its electrochemical cells - the chemicals of the electrolyte react with the electrodes

•one end or “terminal” will end up with mostly negative charges and the other will have mostly positive charges

• the negative charges (at the negative terminal) are attracted to the positive charges (at the positive terminal)

Define:POTENTIAL DIFFERENCE (OR VOLTAGE): difference in electric potential energy between two points that will cause current to flow in a closed circuit• the higher the potential difference, the greater the potential energy of each

electron•potential difference is measured with a voltmeter, which is placed across the

positive and negative terminals of a battery• the unit for measuring potential difference is the volt (V)

How Electrons Transfer Energy in a Circuit page 438

•picture electrons being like water in a hose: if the hose already has water in it, when you turn the tap on water will immediately come out

• this is why when you turn the light switch on, a light bulb will turn on immediately!•when an energy source is connected to the circuit, electrons in the conductor push

or repel other electrons nearby (kind of like dominoes)

Current page 439

Define:ELECTRIC CURRENT: a measure of the amount of electric charge that passes by a point in an electrical circuit each second.• current from a battery flows in only one direction: this is called direct current (DC)• the current that flows through cords plugged into the wall is called alternating

current (AC)• it flows back and forth at regular intervals called cycles• this is the current that comes from generators and carried by power lines to your


REMEMBER (bottom of page 440): When you connect an ammeter or a voltmeter to a circuit, connect the negative terminal of the meter to the negative terminal of the electrical source and he positive terminal of the meter to the positive terminal of the electrical source.

homeMeasuring Current• current in a circuit is measured using an ammeter• the unit of electric current is the ampere (A)

Define:AMPERE: unit of electric current, a measure of the amount of charge moving past a point in the circuit every second

Resistance pg. 441

Define:RESISTANCE: degree to which a substance opposes the flow of electric current through it

•all substances resist electron flow to SOME extent•good conductors have low resistance; good insulators have low resistance• resistance is measured in ohms (Ω) using an ohmmeter•when a substance resists the flow of electrons, it slows the current and converts

electrical energy into other forms of energy•more resistance means the more energy it gains from the electrons that pass

through it•energy gained is radiated out to surroundings usually as light or heat

Resistance in a Circuit• more resistance = less conductivity• example: filament in a lightbulb is a resistor which allows it to heat up and give

light

Resistors and Potential Difference• in a circuit electrons have high potential difference as they enter a resistor

compared to when they leave because they use up energy by passing through the resistor

Resistance in a Wire• think as the flow of electrons as a flow of water through a pipe

• the longer and thinner a pipe is, the more resistance it has to the flow of water (OR it takes longer to drain a bucket with a straw than a 1 inch pipe)

• current (flow of electrons) decreases (flow slows down) as you add resistance


11.1 QUESTIONS

1)In the table below describe what the following parts in the circuit above, do.

Electric Circuit Part What the parts do

Battery (or Source) The battery gives the Coulombs their energy by lifting them to higher voltage( potential).

Conductor (wires) The conductor passes the Coulombs along without changing their energy.

Switch The switch allows the Coulombs to pass or not.Insulator An insulator does not allow all Coulombs to pass.Ammeter An ammeter counts the number of Coulombs passing a particular

point every second.

Volt”meter” The voltmeter measures how much energy the Coulombs lost while falling through the light bulb or gained while raised through the battery.

Light Bulb The light bulb changes the Coulombs electrical energy into heat and light energy.

2)What is the difference between an electrode and an electrolyte?Electrodes are the metals strips that react with electrolytes in an electrochemical cell

3)What is another name for stored energy? potential energy

4)What does potential difference measure? measures the difference in electric potential energy between two points that will cause current to flow in a closed circuit

5) When you turn a light switch on in your room, how is it possible that the turns on immediately? Does the same electron travel all the way from the switch to the light? No, the electrons at the switch repel the electrons beside them creating a chain reaction which eventually reaches the lamp.

6)How do resistors use the flow of electrons? What is the result? (Hint: What do you see in a lightbulb that means current is flowing through it?) Resistors use up the energy from the electrons. You can see this by the resistor producing heat, light, etc.

7) Complete this chart:

Quantity Unit Symbol Measured with

potential difference volts V voltmeter

current ampere A ammeter

resistance ohms Ω ohmmeter


11.2 SERIES CIRCUITS AND PARALLEL CIRCUITS

Circuit Diagrams pg. 450

• symbols make it easier to plan and analyze a circuit before you build it• drawings using these symbols are called circuit diagrams• RULES: Always use a ruler to draw lines. Make right angle corners so that your finished diagram is a rectangle.

Complete this chart (Table 11.2):

Schematic Symbol Part Name Function

wire conductor; allows electrons to flow

cell, battery electrical source; longer side is the positive terminal; shorter side is the

negative terminal

switch opens and closes a circuit

lamp/light bulb specific load; converts electricity to light and heat

resistor general load; converts electricityto heat

ammeter measures current through a device,connected in series

voltmeter measures voltage across a device, connected in parallel

Draw the Schematic Circuit Diagram for the circuit below. Remember conductors are represented with horizontal or vertical lines.

NOTE: Voltmeters are placed across a component of the circuit. Ammeters are placed anywhere along the circuit.


Series Circuits pg. 451

Define:SERIES CIRCUIT: electric circuit in which the components are arranged one after another in series.

•electrons can only follow one path - if this pathway is disrupted, the whole circuit cannot function

• the amount of current is the same in all parts of the circuit

• if you add more resistors, you increase the total resistance of the circuit and therefore decrease the current

• if you decrease current, would the lightbulbs shine brighter or dimmer?

•electrons use up all their potential difference going around a series circuit no matter how many loads are in the circuit

•adding batteries in series increases VOLTAGE

Parallel Circuits pg. 451Define:PARALLEL CIRCUIT: electric circuit in which the parts are arranged so that electrons can flow along more than one path.• the points where a circuit divides into different paths or where paths combine are

called junction points (See Figure 11.28 below)• an interruption in one pathway does not disrupt affect other pathways• also, adding a new pathway with more resistors does not affect the resistance in any

of the other pathways


Circuit Diagram

• adding extra resistors decreases the total resistance of the circuit (like drinking through two straws instead of one)

• electrons will look for the path of least resistance and so the current will be higher in areas with less resistors (see Figure 11.29 below)

Complete this table (Table 11.3)

Circuit Potential Difference Current Resistance

Series Circuit Each load uses a portion of the total potential difference supplied by the battery

The current is the same throughout a series circuit

The current decreases when more resistors are added

Parallel Each load uses all the potential energy difference supplied by the battery

The current divides into different paths. A pathway with less resistance will have a greater current.

Adding resistors in parallel decreases the total resistance of the circuit


The voltmeter is shown here to be measuring potential difference around the lamp.

The ammeter is shown here to be measuring current between

the lamp and the negative terminal of the battery.

QUESTIONS: SERIES CIRCUITS1. T/F: In order to connect an ammeter to a circuit you must break the circuit and insert the meter.

2. T/F: In order to connect a voltmeter to a circuit you measure around the circuit component.

3. A Light Bulb, Motor, Electrical Heater, Radio can all be referred to as a LOAD.

4. Label all the points indicated on the circuit diagram (A, B, C, D) on the circuit picture below.

5. What kind of circuit is the one above? series

6. If you were to have more than one lightbulb in this circuit, how would this affect the voltage? half the voltage for each lightbulb

7. If If you were to add lightbulbs to this circuit, how would that affect the resistance? more resistance

8. If you added 1 more lightbulb and one of the two burnt out, what would happen to the other lightbulb? Why? both would go out because the curcuit is broken and there’s only one path for electrons to flow.

9. Draw the schematic drawing for the circuit shown below.

Circuit Picture Circuit Diagram


1. Create a circuit in which,

A) the switch controls current returning to the power supply,B) two bulbs are connected in SERIESC) Draw the circuit diagram.


A) three bulbs connected in SERIESB) the switch controls the current between the 2nd and 3rd bulb,C) voltage is measured across the last bulb.D) Draw the circuit diagram.


A) four bulbs connected IN SERIESB) a switch controls the current between the 3rd and 4th bulb,C) voltage is measured across the first two bulbs, andD) voltage is measured across the last two bulbs.E) Draw the circuit diagram.


Wire the circuits shown and complete the table. Circuit Picture Schematic Diagram Reading on

AmmeterReading on Voltmeter

~0.5A -6V

~0.5A -6V

~0.5A -6V

~0.5A -6V

~0.5A -6V

~0.5A -6V

~0.5A +6V

What do you notice about the voltage of each circuit? all the same

What do you notice about the amperage of each circuit? all the same

How many paths can electrons travel in each of the above circuits? 1

Each circuit above is an example of a series circuit.


REALITY CHECK - Wiring Real Circuits Wire the circuits shown.Record the meter readings and compare bulb brightness.Note all meters do not have to be connected at once. Connect the meter in one particular position, take the reading, remove it and reconnect it in the next position.

Schematic Diagram Voltage (Volts) Voltage (Volts)

Current (Amperes) Current (Amperes)

Bulb Brightness

VT

AT

The brightness of the bulbs in this example will be compared to the circuits in the next two steps (below).

V1 A1


VT AT More? Less?Same? brightness compared to above V1 A1

More? Less?Same? brightness compared to above

V2 A2


VT AT


V1 A1


V2 A2


V3 A3



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ELECTRICITY MINI-LAB: SERIES CIRCUITS

Create the series circuits as shown below. You will have to test the amperage with the ammeter and the voltage with the voltmeter one at a time (since you’ll be using the multimeter).

Picture Circuit Diagram Reading on Ammeter

Reading on Voltmeter

~0.5A -6V

~0.5A -6V

~0.5A -6V

~0.5A -6V

~0.5A +6V

What do you notice about the voltage of each circuit? all the same

What do you notice about the amperage of each circuit? all the same

How many paths can electrons travel in each of the above circuits? 1

Each circuit above is an example of a series circuit.

Use the results from your table to answer the following:

1) In any series circuit, what can you say about the amount of current measured anywhere in the circuit?

The current is the same everywhere in the circuit.

2) In a circuit containing ONE bulb, the voltage drop across the bulb is about higher?/lower?/equal to? the voltage gain across the source. (Circle one)

3) In a series circuit containing TWO identical bulbs, the voltage drop across each bulb is about half the voltage gain across the source.

4) In a series circuit containing THREE identical bulbs, the voltage drop across each bulb is about one third the voltage gain across the source.

5) Look at the circuit below; As more bulbs are connected in series,

A) the brightness of each bulb gets dimmerB) the size of the current becomes less because of more resistanceC) the number of paths for the current stays the same

6) In a series circuit, if one light bulb burns out,A) the current stopsB) the brightness of the remaining bulbs goes out

7) Switches are connected in series to what they control in the circuit.

8) Ammeters are connected in series to what they are measuring the current through.

9) In order to connect a ammeter to a circuit you must break the circuit and insert the meter in series.

QUESTIONS: PARALLEL CIRCUITS

1) When bulbs (or anything else) are connected side by side so that the current must divide at branch points, we call it a parallel circuit.

2) In the above circuit, if the voltage (potential) gain across the source is 1 Volt, what does our model predict about the voltage drop across the light bulb will be? Explain.

All model predicts that the voltage (potential) drop across the light bulb will be 1 Volt. The Coulombs have to fall this distance to return to the battery.

3) What does our model predict the voltage drop across the other light bulb will be? Explain.

All model predicts that the voltage (potential) drop across the light bulb will be 1 Volt. The Coulombs have to fall this distance to return to the battery. The other light bulb in parallel makes no difference to the distance the Coulombs have to fall.

4) If the voltage drop across the light bulbs is the same, what does our model predict the current through the bulbs will be? Explain.

If the light bulbs are the same and the Coulombs give up the same amount of energy as they fall through the light bulbs, then the current will stay the same.

5) Assume both bulbs are identical. In the above circuit, if the electric current through Ammeter (C) is one coulomb per second, then the current through Ammeter (B) will be one coulomb per second. What does our model predict about the electric current through Ammeter (A)? Explain.

Because the light bulbs are identical to current through ammeters (B) and ammeter (C) will be the same. If both light bulbs and one Coulomb per second then, every second two Coulombs must be supplied through ammeter (A)

6) If more bulbs are connected in parallel, what does our model predict about the brightness of each bulb? Explain

Our model predicts the brightness of each light bulb will be the same. This is because the amount of energy each Coulomb loses as it falls to the bulb stays the same.

7) If more bulbs are connected in parallel, what does our model predict about the current in the main circuit [Ammeter (A)]?

The current in the main circuit will increase as it supplies Coulombs each second to more and more light bulbs.

8) If more bulbs are connected in parallel, what does our model predict about the current in the branches [Ammeter (B) and Ammeter (C) or any additional ammeter ]?

The current through each light bulbs stays the same because the Coulombs are falling the same distance (losing the same amount of energy) through identical light bulbs.

9) As more bulbs are connected in parallel, what will happen to the number of paths for the current to flow?

The number of paths increase because each additional like bulb adds another path for the Coulombs to flow.

10) In a parallel circuit, if one light bulb burns out, what does our model predict will happen to A) the current in the main circuit [Ammeter (A)]?

The main branch current will decrease .

B) the current in the branch circuits [Ammeter (B) or (C)]?

The current in the branch circuits will stay the same. They are unaffected by the other branches.

C) the brightness of the remaining bulbs?

The brightness of the remaining bulbs will say the same because the current stays the same.

11) Is there ever any parallel circuit where one branch gets all the current and the other gets none ?

Great question. -- The other branch could be an open switch, a broken wire, a really high resistance in one of the branches or the Voltmeter!

Even More Practice Connecting Circuits & Drawing Schematic Diagrams Draw lines on the following diagrams to represent conductors in order to complete the circuits as stated.

1) Create a circuit in whichA) the switch controls all current leaving the power supply,B) two bulbs are connected in PARALLEL,C) voltage is measured across each bulb.D) Draw the circuit diagram for this circuit.

2) Create a circuit in which A) three bulbs are connected in PARALLEL,B) one switch controls only one bulb,C) the other switch controls all three bulbs,D) voltage is measured across any one bulb,E) Assume power supply produces 12 volts write the voltmeter reading beside the each meterF) Draw the circuit diagram for this circuit.

3) Create a circuit in which A) the switch controls ALL current leaving the power supplyB) the current flowing out of the power supply is measured with an ammeter.C) two bulbs are connected in parallel,D) the current flowing through one of the bulbs is measured with an ammeter.E) Assume power supply produces 6 amperes write the ammeter reading beside the each meterF) Draw the schematic diagram for this circuit.

4) Label all the points (A, B, C, D, E, F) indicated on the circuit picture on the schematic diagram.

Assume the power supply produces 6 amperes and 12 volts, write the expected readings beside the each meter.

5) Label all the points (A, B, C, D, E) indicated on the schematic diagram, on the circuit picture.

EXTRA PRACTICE: Textbook questions

page 457: #3-7

REALITY CHECK - Wiring Real Circuits Wire the parallel circuits shown.Record the meter readings and compare bulb brightness.Note all meters do not have to be connected at once. Connect the meter in one particular position, take the reading, remove it and reconnect it in the next position.

Schematic Diagram Voltage (Volts) Voltage (Volts) Voltage (Volts)

Current (Amperes) Current (Amperes) Current (Amperes)

Bulb Brightness

VT VT+10V

AT

AT

0.67A The brightness of the bulbs in this example will be compared to the circuits in the next two steps (below).

V1 V1-10V

A1 A10.67A


VT VT +10V AT AT 1.33V More? Less?Same? brightness compared to above

V1 V1 -10V A1 A1 0.67A


V2 V2 -10V A2 A2 0.67A


VT +10V+10V AT 2.0A2.0A More? Less?Same? brightness compared to above

V1 -10V-10V A1 0.67A0.67A


V2 -10V-10V A2 0.67A0.67A

More? Less?Same? brightness compared to above V3 -10V-10V A3 0.67A0.67A


Use the results from your table to answer the following;1) In any parallel circuit, what can you say about the voltage drop across any bulb is about the same as the voltage gain across the source?

2) In a circuit containing - ONE bulb, the current through the source is about equal to the current through the bulb." -"TWO identical bulbs, the current through the source is about two times the current through each bulb. -"THREE identical bulbs, the current through the source is about three times the current through each

bulb.

3) Look at all three circuits; As more bulbs are connected in parallel,A) the brightness of each bulb stays the sameB) the current in the main circuit increasesC) the current in the branches stays the sameD) the number of paths for the current increases

4) In a parallel circuit, if one light bulb burns out,A) the current in the main branch decreases B) the brightness of the remaining bulbs stays the same

5) Voltmeters are connected in parallel to the rest of the circuit.

CELLS AND BATTERIES Sources (Batteries) in Series and Parallel

Sources (Batteries) Connected in Series1) Draw a schematic diagram of three sources (6V batteries) connected in SERIES, connected to 1 light bulb.

2) TRY IT! (#1)

3) Measure the voltage/potential difference across the light bulb.A) The voltage is 18 V.B) Each battery is 6 V. C) Therefore, connecting batteries in series will cause the voltage to increase

(increase/decrease) (add all voltages together).

4) Sources connected in series will cause the current through the light bulb to increase (increase/

decrease). You can tell because the bulb gets brighter (brighter/dimmer). TRY IT!

5) As more sources are connected in series to a light, A) the brightness of the bulb will increase (increase/decrease).B) the current will increase (increase/decrease).

C) the voltage across the light will increase (increase/decrease). TRY IT! 6) If one of TWO sources connected in series to a light, is reversed, the voltage will decrease

(increase/decrease) and the current will decrease (increase/decrease). TRY IT!

Sources (Batteries) Connected in Parallel1)Draw a Schematic diagram of three 6V batteries connected in PARALLEL, connected to 1 light

bulb.

2) TRY IT! (#1)

3) Measure the voltage/potential difference across the light bulb.A) The voltage is 6 V.B) Each battery is 6 V. C) Therefore, connecting batteries in parallel will cause the voltage to stay the

same (increase/decrease/stay the same).

Note: “TRY IT!” means create

the circuit with actual materials.

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Sources connected in parallel do not change the current through the load.

The cells in a battery are connected in parallel in order to make each cell last longer.

4) Connect another lightbulb to your circuit. TRY IT! As more sources are connected in parallel to a light,A) the brightness of the light will stay the same (increase/decrease/stay the same)B) the current thought each bulb will stay the same (increase/decrease/stay the same)C) the voltage across the bulb will stay the same (increase/decrease/stay the same)

5) If one of THREE sources connected in parallel to a light bulb, is reversed, the voltage across the light will decrease (increase/decrease) and the current through the light will decrease (increase/

decrease). TRY IT!

Cells and Batteries

1) What is the difference between a cell and a battery? a battery is a bunch of cells connected in series or parallel

2) The cells in a battery are connected in parallel, in order to make each cell last longer.

3) Draw a schematic of the cells in a 9 V battery made from 1.5 V cells.

4)Draw a schematic of the cells in a 6 V lantern battery made from 8(eight) - 1.5 V cells.

5) The cells of a 6 V lantern battery connected in series in order to increase voltage

6) The cells of a 6 V lantern battery connected in parallel in order to increase cell life

7) State whether the following sources are a SERIES OR PARALLEL connection and indicate the TOTAL VOLTAGE.

_____________ circuit ____________ circuit

Total Voltage = _____ V Total Voltage = _____ V

11.3 RESISTANCE - Ohm’s Law

Resistance is a term used in current electricity to describe things like light bulbs, motors, heaters,

stereos, etc. All of these things are called Loads and convert the energy the electrons carry, into other forms.

Things with a lot of resistance need a lot of energy to make them move. Things with little resistance don’t need very much energy at all to make move.

In both models Resistance makes it hard for the electrons to flow. Resistance is often

described as an opposition to the flow of current.

Resistance is measured in units called ohms (Ω).

Ohm’s LawOhm’s Law shows how the voltage, current, and resistance affect each other. In a simple circuit, if the voltage increases, what would you predict would happen to the current? If the resistance somehow was increased, and the voltage stayed the same, what would happen to the current through the circuit.? We can use mathematical equations to qualitatively predict what will happen in these cases.

If we wish to know the measured values for the different variables, we have to use Ohm’s Law.

In words, Ohm’s Law states: the potential difference between two points on a conductor is proportional ( directly related) to the electric current flowing through the conductor.

This law puts three variables (V, I, R) into a mathematical formula.

Read horizontally: multiplication

Read vertically: division

or

REMEMBER:

Symbol Unit Measures

V volts, V voltage/ potential difference

I amperes, A current

R ohms, Ω resistance

To problem solve using mathematical formulas:

1. Record your givens: Read problem carefully and record all given quantities, using correct symbols and units.

2. Equation: Write the formulas related to the problem.3. Substitute: Ensure data is in the correct units. Substitute given quantities into

the formula.4. Calculate: Record with correct units.5. Answer: Write an answer statement in sentence form.

Example Problem #1Given V = ?

I = 3 AR = 2 Ω

Find: VUse: V = IR (from the triangle)

= 3 A x 2 Ω

= 6 V

Example Problem #2Given V = 3 V

I = ?R = 2 Ω

Find: I

Use: (from the triangle)

= 1.5 A

Ohm’s Law ProblemsPlease complete on a separate sheet of paper.

1. What is the current produced by a potential difference of 240 volts through a resistance of 0.2 ohms?

2. What resistance would produce a current of 120 amps from a 6 volt battery?

3. What is the current produced by a 9 volt battery flowing through a resistance of 2 x 10 –4 ohms?

4. What is the potential difference if a resistance of 25 ohms produces a current of 250 amperes?

5. What is the current produced with a 9 volt battery through a resistance of 100 ohms?

6. Find the current when a 12 volt battery is connected through a resistance of 25 ohms.

7. If the potential difference is 120 volts and the resistance is 50 ohms, what is the current?

8. What would be the current in Problem 3 if the potential difference were doubled?

9. What would be the current in Problem 3 if the resistance were doubled?

10.What resistance would produce a current of 200 amperes with a potential difference of 2000 volts?

11.A 9 volt battery produces a current of 2.0 amperes. What is the resistance?

12.An overhead wire has a potential difference of 2000 volts. If the current flowing through the wire is one million amperes, what is the resistance of the wire?

13.What is the resistance of a light bulb if a 120 volt potential difference produces a current of 0.8 amperes?

14.What voltage produces a current of 50 amps with a resistance of 20 ohms?

15.Silver has a resistance of 1.98 x 10-4 ohms. What voltage would produce a current of 100 amps?

16.A current of 250 amps is flowing through a copper wire with a resistance of 2.09 x 10 –4 ohms. What is the voltage?

17.What voltage produces a current of 500 amps with a resistance of 50 ohms?

18.What voltage would produce a current of 100 amps through an aluminum wire which has a resistance of 3.44 x 10 –4 ohms?

TOTAL RESISTANCE OF CIRCUITSSet up the following circuits.Use the multimeter as an Ohmmeter to measure their total resistance.

Total Resistance Total Resistance Total Resistance Total Resistance Series Circuits Total

Resistance(Ohms) (Ω)

Parallel Circuits Total Resistance (Ohms) (Ω)

ΩT = 2Ω ΩT = 2Ω

ΩT = 4ΩΩT = 1Ω

ΩT = 6ΩΩT = 0.6Ω

Use the results from the notes and your table to answer the following;

1)What is the resistance?Resistance describes how difficult it is for the current to flow through something. Things with highresistance make it very difficult for the current to flow. Current flows easily through things withlittle resistance.2) As more lights are connected in SERIES: A) the total resistance of the circuit becomes high so we say the load becomes largeB) the (easier/harder/the same) for the battery to push coulombs through the circuit.C) the current in the circuit becomes lower .

3) As more lights are connected in PARALLEL: A) the total resistance of the circuit becomes low so we say the load becomes small.B) it is (easier/harder/the same) for the battery to push coulombs through the circuit.C) the higher the current in the main circuit.

Short Circuits (fill in the blanks from the textbook, page 462)

• SHORT CIRCUIT: an accidental low resistance connection between two points in a circuit causing excess current flow (usually caused by some sort of damage to the wire)

• this excess flow can cause overheating and/or a fire• examples: a powerline is knocked down in a storm

• torn wires no longer provide a complete path for electrons to flow• if you come in contact with the wire, the electricity will use your body as a path to

the ground

11.1 current electricity electrochemical cells (the energy...

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