ch22.1 – current electricity. to get a current (a flow of charged particles), need to create a...

Ch22.1 – Current Electricity

Ch22.1 – Current Electricity

To get a current (a flow of charged particles), need to create a potential difference and sustain it.- batteries, generators

Battery - place any 2 different materials in contact, electrons flow

Electronic series for several metals

Ex1: what is the potential difference between:

1) Gold and copper?

2)Silver and lithium?

3) Iron and potassium?

4) Zinc and copper?

5) Copper and nickel

LithiumPotassium SodiumAluminumZincIronNickelTinLeadHydrogenCopperMercurySilverPlatinumGold

-3.0V-2.9V-2.7V-1.7V-.76V-.44V-.26V-.14V-.13V 0V .34V .8V .8V 1.2V 1.3V

Electronic series for several metals

Ex1: what is the potential difference between:

1) Gold and copper?

2)Silver and lithium?

3) Iron and potassium?

4) Zinc and copper?

5) Copper and nickel

(1.3V) – (.34V) = .96V

(.8V) – (-3.0V) = 3.8V

(-.44V) –(-2.9V) = 2.46V

(.34V) – (-.76V) = 1.10V

(.34V) – (-.26V) = .6V

LithiumPotassium SodiumAluminumZincIronNickelTinLeadHydrogenCopperMercurySilverPlatinumGold

-3.0V-2.9V-2.7V-1.7V-.76V-.44V-.26V-.14V-.13V 0V .34V .8V .8V 1.2V 1.3V

Current (I) - rate at which charge flows

Amps = Coulombs sec I =

q

t

Ex2: The belt on the Van de Graaf generator carries 20µC of charge to the sphere when it rotates in 2 seconds. Determine the current.

Ex3: The starter motor in a car draws 180A of current from the battery in about 2 seconds. How much charge is flowing thru the circuit?

Black BrownRedOrangeYellowGreen BlueVioletGrayWhiteGoldSilver

0123456789+/- 5%+/- 10%

Color CodeEx4) What is the resistance of:

Red, green, blue, gold

Ex5) brown, black brown, gold

Ex6) Color stripes for 4000Ω +/-10%

Ch22 HW #1

Resistance (R) – resists the flow of current. Symbol:

- usually made of semi conductive materials, like carbon - resistors are small usually, so use a color code to ID

Resistance (R) – resists the flow of current. Symbol:

- usually made of semi conductive materials, like carbon - resistors are small usually, so use a color code to ID

Black BrownRedOrangeYellowGreen BlueVioletGrayWhiteGoldSilver

0123456789+/- 5%+/- 10%

Color Code Ex4) What is the resistance of:Red, green, blue, gold

25 x 106Ω +/-5%

Ex5) brown, black brown, gold

10 x 101Ω +/-10%

Ex6) Color stripes for 4000Ω +/-10%

Yellow, black, red, silver

Ch22 HW #1

Lab22.1 Batteries

- Lab due tomorrow

- Ch22 HW#1 due at beginning of period

Ch22 HW#1 1 – 101. What is the potential for a wet cell battery made with

nickel and zinc?

2. What is the potential for a wet cell battery made with Al and mercury?

3. What is the potential for a wet cell battery made with Pt and Cu?

4. What is the potential for a wet cell battery made with sodium and tin?


nickel and zinc?-.76 – (-.26) = .5V

2. What is the potential for a wet cell battery made with Al and mercury?-1.7 – (.80) = 2.5V

3. What is the potential for a wet cell battery made with Pt and Cu?

4. What is the potential for a wet cell battery made with sodium and tin?


nickel and zinc?-.76 – (-.26) = .5V

2. What is the potential for a wet cell battery made with Al and mercury?-1.7 – (.80) = 2.5V

3. What is the potential for a wet cell battery made with Pt and Cu?.34 – (1.2) = .86V

4. What is the potential for a wet cell battery made with sodium and tin?-.14 – (-2.7) = 2.56V

5. What is the current when 25 C of charge pass by a point in 10 seconds?

6. What is the current when 4.5 C pass by a point in 3.2 seconds?

7. What is the resistor with the colors: gray, green, red, silver?

8. What is the resistor with the colors: red, green, brown, gold?

9. Write the color band for a 1000, +/- 5% resistor.

10. Write the color band for a 300,000, +/-10% resistor.

5. What is the current when 25 C of charge pass by a point in 10 seconds?I = q/t = 25C/10s = 2.5A

6. What is the current when 4.5 C pass by a point in 3.2 seconds?






6. What is the current when 4.5 C pass by a point in 3.2 seconds?I = q/t = 4.5x10-6C/3.2s = 1.4x10-6A







7. What is the resistor with the colors: gray, green, red, silver?85x102Ω ± 10%







8. What is the resistor with the colors: red, green, brown, gold?25 x 101Ω ± 5%







9. Write the color band for a 1000, +/- 5% resistor.brown, black, red, gold






9. Write the color band for a 1000, +/- 5% resistor.brown, black, red, gold

10. Write the color band for a 300,000, +/-10% resistor.orange, black, yellow, silver

Ch22.1Equivalent resistanceWhen resistors are in series (one attached to next, etc),

just add them up. Req = R1 + R2 +…

Ex1) What is the equivalent resistance?

2Ω 3Ω

1Ω 2Ω 3Ω

4Ω 4Ω 4Ω 4Ω

Ch22.1Equivalent resistanceWhen resistors are in series (one attached to next, etc),

just add them up. Req = R1 + R2 +…

Ex1) What is the equivalent resistance?

2Ω 3Ω

1Ω 2Ω 3Ω

4Ω 4Ω 4Ω 4Ω

= 5Ω

= 6Ω

= 16Ω

When resisters are in parallel (on different branches), use formula:

Ex2) Find Req :

2Ω

2Ω

3Ω

4Ω

5Ω

5Ω

5Ω

...111

21

RRReq

Complicated resistors:Ex3) Find Req:

1Ω

1Ω

1Ω

=1Ω

1Ω

1Ω

1Ω 1Ω

1Ω

=

Complicated resistors:Ex3) Find Req:

1Ω

1Ω

1Ω

=

1Ω .5Ω =1.5Ω

1Ω .86Ω

1Ω

1Ω

1Ω

1Ω 1Ω

1Ω

1Ω2Ω

1Ω.5Ω 1.5Ω

2Ω1Ω

1.86Ω

=

=

=

Ohm’s Law - voltage, current, & resistance are related by:

V= I.REx4) A 12V battery is attached to 100Ω resistor.

What current passes through the circuit?

Ex5) A 20V battery pushes 2A thru a circuit. What kind of resistance does it feel?

100Ω12V

I = 2A

20V ?

Ch22 HW#2 11-20

Ch22 HW#2 11 – 20For 11 – 14, what is the equivalent resistance of:11. Two 10 resistors in series.

10 10

12. Two 10 resistors in parallel. 10

10 13. A 10 , 25 , and a 35 resistor in series.

10 25 35

14. A 300 and a 150 resistor in parallel. 300

150


10 10 = 20


= 5


10 25 35


150


10 10 = 20


= 5


10 25 35 = 70


= 100

150

What is the equivalent resistance of:15.

5 10 12 =

16. 12

=

6 17. 20

20 =

20

20


5 10 12 = 27

16. 12

= 4

6 17. 20

20 =

20

20


5 10 12 = 27

16. 12

= 4

6 17. 20

20 = 5

20

20

18. A 9 V battery feels a resistance of 18 in the circuit it is attached to. How much current will it produce?

19. A 1.5 V D-Cell battery produces 0.75 A when in a circuit. How much resistance is in this circuit?

20. A 100 resistor has 1.1 A passing through it. What kind of voltage might cause this?

18Ω9V

I = .75A

1.5V ?

I=1.1AV=? R=100




18Ω9V

I = .75A

1.5V ?

I=1.1AV=? R=100

AV

R

VI 5.0

18

9




18Ω9V

I = .75A

1.5V ?

I=1.1AV=? R=100

AV

R

VI 5.0

18

9

275.0

5.1

A

V

I

VR




V = I.R = (1.1A)(100Ω) = 110V

18Ω9V

I = .75A

1.5V ?

I=1.1AV=? R=100

AV

R

VI 5.0

18

9

275.0

5.1

A

V

I

VR

2Ω

2Ω2Ω 2Ω

2Ω 2Ω

2Ω

2Ω

Ch22.1 cont.

1)

=

Ex2)

4Ω 4Ω

8Ω

8Ω

8Ω5Ω

10Ω

10Ω10Ω

Current - in a series circuit, current stays the same through out circuit. - in a parallel circuit, current splits up to the branches.

A

1) 5Ω

4Ω

Ex3) How much does each ammeter read?

3V

Current - in a series circuit, current stays the same through out circuit. - in a parallel circuit, current splits up to the branches.

A

1) 5Ω

4Ω

Req : 5+4 = 9

V 3VReq 9Ω

I = = = .33A

Ex3) How much does each ammeter read?

3V

A

15Ω 10Ω

2)

18V

A

15Ω 10Ω

2)

V 50VReq 6Ω

I = = = 8.3A

18V

3)

2Ω

10V 12Ω 6Ω

A

4)

12V

4Ω 4Ω

AA1 A2

5)

18V

3Ω 6Ω

Ch22 HW#3 21 – 27

AA1 A2

Ch22 HW#3 21 – 27

21.

22.

23.

6Ω

6Ω2Ω

8Ω

12Ω

12Ω

8Ω

3Ω

2Ω

2Ω

3Ω

Ch22 HW#3 21 – 27

21.

= 5Ω

22.

23.

6Ω

6Ω2Ω

8Ω

12Ω

12Ω

8Ω

3Ω

2Ω

2Ω

3Ω

Ch22 HW#3 21 – 27

21.

= 5Ω

22.

= 9.6Ω

(4.8Ω) (4.8Ω)

23.

6Ω

6Ω2Ω

8Ω

12Ω

12Ω

8Ω

3Ω

2Ω

2Ω

3Ω

Ch22 HW#3 21 – 27

21.

= 5Ω

22.

= 9.6Ω

(4.8Ω) (4.8Ω)

23. = 2.5Ω

6Ω

6Ω2Ω

8Ω

12Ω

12Ω

8Ω

3Ω

2Ω

2Ω

3Ω

24.

1Ω

1Ω1Ω

1Ω

1Ω

1Ω1Ω

1Ω

24.

= 8Ω

1Ω

1Ω1Ω

1Ω

1Ω

1Ω1Ω

1Ω

25. What does the ammeter read?


A

5Ω12V

A

3Ω

2Ω10V



A

5Ω12V

A

3Ω

2Ω10V

AV

R

VI 4.2

5

12



A

5Ω12V

A

3Ω

2Ω10V

AV

R

VI 4.2

5

12

AV

R

VI

eq

25

10


A

4Ω12V

2Ω

4Ω


A

4Ω12V

2Ω

4Ω

AV

R

VI

eq

34

12

Ch22.4 – Energy and Power

Power is the rate that energy is used. Units:

Ex1) A 6.0V battery delivers 0.50A to an electric motor. What powerdoes it consume?

R

VP

RIP

VIP

2

2

Electric Energy

- measured in Joules or kilowatt-hours

- conversion: 1kW.hr = 3.6x106J

tVIE

tPE

Ex2) A heater has a resistance of 10Ω, and operates at 120V.a) What is the current?

b) What thermal energy is supplied by the heater in 10s?

Ex3) A TV draws 5.0A when operated at 120V.a) How much power does it use?

b) If the set operates for 5hrs per day for 30 days, how much energy does it use?

c) At $0.50 per kW-hr, what does it cost?

For your lab tomorrow:

Heat energy warms the water:

Q = m.Cp.ΔT

A circuit supplies the electrical energy:

E = I.V.t

Conservation of energy:

I.V.t = m.Cp.ΔT change in temp of H2O

Voltmeter clock mass specific (5 min) of H2O heat

Ch22 HW#4 28 – 33

Lab22.2 – Electric Heat

- lab due tomorrow

- Ch22 HW#4 due at beginning of period

Ch22 HW#4 28 – 3328. A 12 V battery is supplying 180 A of current to a starter motor.

How much power is it dissipating?

29. A 100 resistor has 2 A flowing through it. How much power is it dissipating?

30. The Hoover Dam produces 22,000 V at 50 A. What power is it producing?

Ch22 HW#4 28 – 3328. A 12 V battery is supplying 180 A of current to a starter motor.

How much power is it dissipating?

29. A 100 resistor has 2 A flowing through it. How much power is it dissipating?

30. The Hoover Dam produces 22,000 V at 50 A. What power is it producing?

)12)(180( VAVIP

)100()2( 22 ARIP

)000,22)(50( VAVIP

31. The electrical wires between Hoover Dam and Victorville have a total of 100 of resistance. (That’s pretty small for so many miles of wire!)If the Hoover Dam energy produced were sent at 50 A, how muchpower would be dissipated by the time the energy reached us?!?

32. A heater has a resistance of 25 and operates at 110 V. What amount of electrical energy is converted to thermal energy in 1 minute?

33. A TI-89 calc draws 0.1 A when powered by its four AAA batteries. (That’s 6 V folks!) How much energy does it consume in 5 minutes?

31. The electrical wires between Hoover Dam and Victorville have a total of 100 of resistance. (That’s pretty small for so many miles of wire!)If the Hoover Dam energy produced were sent at 50 A, how muchpower would be dissipated by the time the energy reached us?!?

32. A heater has a resistance of 25 and operates at 110 V. What amount of electrical energy is converted to thermal energy in 1 minute?

33. A TI-89 calc draws 0.1 A when powered by its four AAA batteries. (That’s 6 V folks!) How much energy does it consume in 5 minutes?

)100()50( 22 ARIP

)60(25

110 22

sV

tR

VE

)300)(6)(1.0()( sVAtVItPE

Ch23.1 – Simple Series and Parallel Circuits

Series - same current throughout circuit

A

45V47Ω

82Ω

Ex 1) a 47Ω and 82Ω resistors are connected in series to a 45.0V battery.a) What does the ammeter read?b) What do the voltmeters read?

V2

V1

Ch23.1 – Simple Series and Parallel Circuits

Series - same current throughout circuit

A

45V47Ω

82Ω

Ex 1) a 47Ω and 82Ω resistors are connected in series to a 45.0V battery.a) What does the ammeter read?b) What do the voltmeters read?

Req = 47 + 82 = 129Ω

a) V 45VReq 129Ω

I = = = .35A

b) VdropR1 = I ∙ R1 = (.35)(47)= 16.4V

VdropR2 = I ∙ R2 = (.35)(82)= 28.6V

V2

V1

Ex 2) A 9V battery is attached to a 400Ω and 500Ω resistors in series. What is the voltage drop across the 500Ω resistor?

9V

400Ω

500Ω

Ex 2) A 9V battery is attached to a 400Ω and 500Ω resistors in series. What is the voltage drop across the 500Ω resistor?

9V

a) Req1 = 900Ω

b) V 9VReq 900Ω

I = = = .01A

c) VdropR2 = I ∙ R2 = (.01)(500)= 5V

400Ω

500Ω

Parallel – current from battery splits between branches

Ex3) A 6 volt battery is attached to 2Ω and 9Ω resistors in parallel. What is the current produced by the battery? What is the current thru each resistor?

9Ω2Ω6V

Parallel – current from battery splits between branches

Ex3) A 6 volt battery is attached to 2Ω and 9Ω resistors in parallel. What is the current produced by the battery? What is the current thru each resistor?

9Ω2Ω6V

b) VdropR1 = 6V VdropR2 = 6V

Req = 1.6Ω

V 6VReq 2Ω

I = = = 3.7A

a)

I1 = = = 3A VdropR1 6V R1 2Ω

I2 = = = .7A VdropR2 6V R2 9Ω

Ex4) 60Ω, 20Ω and 30Ω resistors connected in parallel to a 90V battery.

a) Find Req:b) Find current thru

battery:c) Find current thru

resistors:

60Ω90V 20Ω 30Ω

Ch 23 HW#1 1-5

Ex4) 60Ω, 20Ω and 30Ω resistors connected in parallel to a 90V battery.

a) Find Req:b) Find current thru

battery:c) Find current thru

resistors:

60Ω90V 20Ω 30Ω

a)

b) V 90VReq 10Ω

I = = = 9A

Req = 10Ω

c) I1 = = = 1.5A VdropR1 90V R1 60Ω I2 = = = 4.5A VdropR2 90V

R2 20Ω

I3 = = = 3A VdropR3 90V R3 30Ω

Ch 23 HW#1 1-5

Ch23 HW#1 1 – 51. Three 2 resistors are connected in series to a 12 V battery.

What is current in the circuit?What is the voltage drop across each resistor?

2. A 10 and a 5 resistor are connected in series to a 30 V battery.What is the current in the circuit?What is the voltage drop across each resistor?

2Ω

2Ω12V

10Ω

5Ω30V

2Ω




2Ω

2Ω12V

AV

R

VI

eq

26

12

10Ω

5Ω30V

2Ω VARIVdrop 4)2)(2(




2Ω

2Ω12V

AV

R

VI

eq

26

12

10Ω

5Ω30V

AV

R

VI

eq

215

30

2Ω VARIVdrop 4)2)(2(

VARIV

VARIV

drop

drop

10)5)(2(

20)10)(2(

2

1

3. A 100 resistor, a 75 resistor, and a 125 resistor are connected in series to a 110 V power supply. What is the current in the circuit?

What is the voltage drop across each resistor?

4. A 25 and a 35 resistor are connected in parallel to a 12 V battery.What is the voltage drop across each resistor?What is the current through each resistor?What is the current through the battery?

100Ω

75Ω110V

125Ω

25Ω12V 35Ω



4. A 25 and a 35 resistor are connected in parallel to a 12 V battery.What is the voltage drop across each resistor?What is the current through each resistor?What is the current through the battery?

100Ω

75Ω110V

125Ω

25Ω12V 35Ω

AV

R

VI

eq

37.300

110

VARIV

VARIV

VARIV

drop

drop

drop

8.45)125)(37(.

5.27)75)(37(.

37)100)(37(.

23

22

11



4. A 25 and a 35 resistor are connected in parallel to a 12V battery.What is the voltage drop across each resistor?What is the current through each resistor?What is the current through the battery?

Vdrop = 12V

100Ω

75Ω110V

125Ω

25Ω12V 35Ω

AV

R

VI

eq

37.300

110

VARIV

VARIV

VARIV

drop

drop

drop

8.45)125)(37(.

5.27)75)(37(.

37)100)(37(.

23

22

11

AV

R

VI

AV

R

VI

34.35

12

48.25

12

22

11

AV

R

VI

eq

82.6.14

12

5. A 100 resistor, a 75 resistor, and a 125 resistor are connected in parallel to a 110 V power supply.

What is the voltage drop across the 75 resistor?What is the current through the each resistor?What is the current through the battery?

100Ω110V 75Ω 125Ω

5. A 100 resistor, a 75 resistor, and a 125 resistor are connected in parallel to a 110 V power supply.

What is the voltage drop across the 75 resistor?What is the current through the each resistor?What is the current through the battery?

Vdrop = 110V

100Ω110V 75Ω 125Ω

AV

R

VI

AV

R

VI

AV

R

VI

drop

drop

drop

9.125

110

5.175

110

1.1100

110

33

22

11

AV

R

VI

eq

4.39.31

110

Ch23.3 – Applications

I = ___A I = ___A I = ___A

Short Circuit – circuit with very little resistance creates a very large current.Circuit breaker – automatic switch that opens when the current

gets too high.GFI (Ground Fault Interrupter) – wall outlet that acts like a mini circuit

breaker. (Bathrooms, kitchens, garages)

6Ω12V 3Ω12V 0Ω12V

Ammeter – device that measures current. Connect in line (series).

Must have low resistance so that it doesn’t affect the circuit.

Voltmeter – device that measures voltage. Connect across (parallel).

Must have high resistance so that barely any of the current branchesto that part of the circuit.

RV

RV

Ex1) What does each voltmeter and each ammeter read?

A2

10Ω24V

5Ω

10Ω V

A1

Ex2) What does each voltmeter and each ammeter read?

Ch23 HW#2 6 – 9

A2

10Ω45V

15Ω

7Ω V

A1

Ch23 HW#2 6 – 9 6.

A1

10Ω 10Ω

A2A3

10V

Ch23 HW#2 6 – 9 6.

A1

10Ω 10Ω

A2A3

10V

AV

R

VIA

AV

R

VIA

AV

R

VIA

drop

drop

eq

110

10:

110

10:

25

10:

3

2

1

7.

A3

3Ω

12V

6Ω

A1A2

7.

A3

3Ω

12V

6Ω

A1A2

AV

R

VIA

AV

R

VIA

AV

R

VIA

eq

drop

drop

62

12:

26

12:

43

12:

3

2

1

8.

A4

3Ω

120V

A1

5Ω

A2

7Ω

A3

8.

A4

3Ω

120V

A1

5Ω

A2

7Ω

A3

AV

R

VIAA

V

R

VIA

AV

R

VIAA

V

R

VIA

eq

drop

dropdrop

8148.1

120: 1.17

7

120:

245

120: 40

3

120:

43

21

9.

A1

9Ω 9Ω

A2A3

9V

4.5Ω

9.

A1

9Ω 9Ω

A2A3

9V

4.5Ω

AV

R

VIAA

V

R

VIA

VAAV

R

VIA

dropdrop

eq

5.90

5.4: 5.

9

5.4:

5.4)5.4)(1(V 19

9:

32

drop4.51

Ch22,23 Rev 1 – 10 1. What is the potential for a wet cell battery made with

platinum and copper?

2. Color band for 1000Ω +/-5% resistor?

Req for:

2Ω

2Ω2Ω

2Ω

2Ω

2Ω2Ω

2Ω2Ω

2Ω

4. 12V battery with 150Ω of resistance. How much current?

5. 2 D-cells have a potential of 3.0V, produce 0.90A in a circuit.How much resistance?

6.

100Ω50V 1000Ω

A

7. 110V power supply operates at 25A to run a compressor. How much power is it dissipating?

8. A 135Ω resistor has 3.5A flowing thru it. How much power?

9. Heater with a resistance of 40Ω operates at 110V. How much electrical energy does it convert to thermal energy in 10min?

10. A watch draws 0.005A when powered by its 3.1V battery. How much energy does it consume in 1 day?

11.

a. Req for parallel:b. Req for total:c. I for circuit:d. Vdrops:e. I’s for branches:f. Power from battery:g. Power dissipated by R1.

4Ω 4Ω

A

12V

R1=4Ω

V

ch22.1 – current electricity. to get a current (a flow of charged particles), need to create a...

Documents

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potential difference

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