Fizzix AP – Ch 16, 17, 18 Honors – Ch 17-20 Electrostatics

Fizzix Fizzix AP AP –– Ch 16, 17, 18 Ch 16, 17, 18 Honors Honors –– Ch 17-20 Ch 17-20

Electrostatics

Where are we AP?

• Heat & Thermo–Done… Ch 13-15

• EM–Current… Ch 16-22

Where are we HONORS?

• Heat & Thermo–Done…

• EM–Current… Ch 17-20–Magnetism… Ch 21 & 22–Atomic/Nuclear… Ch 23 & 25

Intro Stuff• Origin of electric charge

–Atoms (duh…)•Nucleus

–P+ & No »Even tho neither exists.

•Electron Shell–e-

Schedoole• Intro PPT

–Practice Probs• LAB

–Discovery : V=IR• Progress Reports/Grades• Whining & Bribes

Intro Stuff• e-

– e=1.60x10-19C– C?

•Coulomb–SI Unit for electric charge–Definition later – Ch19–1C is charge on 6.25 x 1018 e-

Intro Stuff• Law of Electrostatics

–Likes repel, unlikes attract–Since there is an attraction or repulsion, there MUST be a force! Hmmm. F=ma•Coulomb’s Law…

221

rqq

kFe

221

rMM

GFg

Look Familiar?

Intro Stuff• Example? Sure!

–Calculate the ratio of the gravitational and the electrostatic forces experienced by en electron orbiting the nucleus of a basic H atom. 1

1H

Intro Stuff

11

2

21929

2 211

8

5.1 10

1.6 109 10

5.1 10

8.86 10

P ee

e

e

r x mq q

F kr

x CNmF x

C x m

F x N

Intro Stuff

11

2

27 31211

2 211

47

5.1 10

1.67 10 9.11 106.67 10

5.1 10

3.90 10

p eg

g

g

r x mM M

F Grx Kg x Kg

NmF xKg x m

F x N

Intro Stuff

392 10e gF x F

Intro Stuff• Electric Field

–Area around a charge where another charge will feel a force

oqFE

Q

qo

Fe

Fe<0

Fe>0

Attracting Force

Repelling Force

Stimulating Simulations

• Forces between charges• Force Field around a single

charge• Yet another silly animation?• And another?• NO! NOT ANOTHER ONE!!!• This is just SILLY!

FizzixFizzixAP – Ch 16, 17, 18 Honors – Ch 17-20

Electric Potential

Intro Stuff• Potential Energy (‘member?)

–Ball falls from A to B

hA

hb

B

A

BAAB

BAAB

GPEGPEWmghmghW

Intro Stuff• Electical Potential Energy

–Charge ‘falls’ from A to B

dA

db

B

A

BAAB

BAAB

GPEGPEWmghmghW

++++++++++++

- - - - - - - - - - -

BAAB EPEEPEW

Intro Stuff• Electric Potential–‘V’ is the ratio EPE of a qo & the qo itself.

oqEPEV

Intro Stuff• Electric Potential DIFFERENCE

–VB=VA

o

A

o

BAB q

EPEq

EPEVVV

Intro Stuff• Electric Potential DIFFERENCE

o

A

o

BAB q

EPEq

EPEVVV

o

B

qEPE

V

Intro Stuff• Electric Potential DIFFERENCE

o

B

qEPE

V

o

AB

qW

V

Intro Stuff• Electric Potential DIFFERENCE

–Example I n t r o S t u f f• E l e c t i c a l P o t e n t i a l E n e r g y

– C h a r g e ‘ f a l l s ’ f r o m A t o B

d A

d b

B

A

BAAB

BAAB

GPEGPEWmghmghW

+ + + + + + + + + + + +

- - - - - - - - - - -

BAAB EPEEPEW

Work done by qo (2x10-6C) is 5x10-5J. Find V.

VCxJxV

qW

Vo

AB

251021056

5

Intro Stuff• Electron Volt

–Change in PE of an e- when moved through a PD of 1 Volt.

•1eV=1.60x10-19J

Intro Stuff• Capacitors

–C=q/V•Unit is Farad (F)

–C/V=F–Storage of charge–E=½CV2

•Used in MANY places…

Intro Stuff• Capacitor Examples

I n t r o S t u f f• E l e c t i c a l P o t e n t i a l E n e r g y

– C h a r g e ‘ f a l l s ’ f r o m A t o B

d A

d b

B

A

BAAB

BAAB

GPEGPEWmghmghW

+ + + + + + + + + + + +

- - - - - - - - - - -

BAAB EPEEPEW

Intro Stuff• Capacitor Examples

–Keys on keyboard

Intro Stuff• Capacitor Examples

–Electronic flash

Intro Stuff• Capacitor Examples

–Defibrillator

FizzixFizzixAP – Ch 16, 17, 18 Honors – Ch 17-20

Electric Circuits

Intro Stuff• Van de Graaff?

–Charge Pump

Intro Stuff• Van de Graaff?

–Additional Demos•Bubbles•Rice Crispies

–Volunteer???

Intro Stuff• Van de Graaff #’s?

–300,000V–<30A–10,000,000,000

•So just about everything is a ‘conductor’ to it!

Intro Stuff• Circuit?

–Power Supply–Resistance

Battery?• A thing that produces a potential difference

through a chemical reaction.– battery, electric, device that converts chemical

energy into electrical energy. • (How Stuff Works . Com)

• The act of beating or pounding. – Law. The unlawful and unwanted touching or

striking of one person by another, with the intention of bringing about a harmful or offensive contact.

• (Wiki-Idiot-Pedia.comedy)

• For example, here's what happens in one cell of a car's lead-acid battery: – The cell has one plate made of lead and another plate made of

lead dioxide, with a strong sulfuric acid electrolyte in which the plates are immersed.

– Lead combines with SO4 to create PbSO4 plus one electron. – Lead dioxide, hydrogen ions and SO4 ions, plus electrons from

the lead plate, create PbSO4 and water on the lead dioxide plate. – As the battery discharges, both plates build up PbSO4 (lead

sulfate), and water builds up in the acid. The characteristic voltage is about 2 volts per cell, so by combining six cells you get a 12-volt battery.

• A lead-acid battery has a nice feature -- the reaction is completely reversible. If you apply current to the battery at the right voltage, lead and lead dioxide form again on the plates so you can reuse the battery over and over. In a zinc-carbon battery, there is no easy way to reverse the reaction because there is no easy way to get hydrogen gas back into the electrolyte.

Intro Stuff• Electromotive Force

–emf•Maximum terminal V of battery

• Current–Flow of charge t

qI

Intro Stuff

)(Ampere

AsC

tqI

Intro Stuff• Ohm’s Law

–States linear relationship between V & R

))(( OhmAmpVoltIRV

Intro Stuff• Resistance

–Says what it means•e- has to ‘fight’ thru a wire or ‘resistor’

ALR

Intro Stuff• Resistance

–Radio Shack SCAM!

mx

mx

Au

Cu

8

8

1044.2

1072.1

lbozAu

ozlbCu

/56.754,15$/66.984$:

/24.0/87.3$:

Intro Stuff• Power

–Same as regular P, but different

IVPt

qVP

tWP

Intro Stuff• Power…

WattsRIIRIP

IVP2)(

Intro Stuff• Wiring Circuits

–Series / Parallel•Series

VVT 30

100TR

10030

;V

RV

I

So

T

TT

Intro Stuff• Wiring Circuits

–Series / Parallel•Parallel

6301

151

151

1

1111

321

T

T

T

R

R

RRR

R

Intro Stuff• Wiring Circuits

–Series / Parallel•Parallel

15 ?

AI

VRVI

1015150

80

//

////

140118

81080

R

AV

IV

R

10R

Practice Stuff• Boo-ring Book Shtuff

–Ch16 pg437 #12

Practice Stuff• Boo-ring Book Shtuff

–Ch16 pg438 #22

Practice Stuff• Boo-ring Book Shtuff

–Ch17 pg456 #7

Practice Stuff• Boo-ring Book Shtuff

–Ch17 pg456 #14

Practice Stuff• Boo-ring Book Shtuff

–Ch17 pg457 #22

Practice Stuff• Boo-ring Book Shtuff

–Ch18 pg477 #7

Practice Stuff• Boo-ring Book Shtuff

–Ch18 pg477 #12

Practice Stuff• Boo-ring Book Shtuff

–Ch18 pg478 #26

Practice Stuff• Boo-ring Book Shtuff

–Ch19 pg499 #2

Intro Stuff• Wiring Circuits

–Now, DO IT!–LABS 40, 42, 43, & 44