charges & charging · charges & charging electric charges 1. describe existence of...

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1 Electricity Lecture Series Electricity Lecture Series email: email: [email protected] [email protected] ; ; [email protected] [email protected] http:// http:// drjj.uitm.edu.my drjj.uitm.edu.my Applied Sciences Education Research Group (ASERG) Faculty of Applied Sciences Universiti Teknologi MARA Charges & Charging Charges & Charging Electric Charges Electric Charges 1. Describe existence of electrical charges in matter its magnitude, mass, its relative masses, its charges, its quantization property and its conservation property. 2. Apply the quantization and conservation property for certain charging and discharging process 3. Sketch and explain charging by induction and charging by contact numerically and diagrammatically. Objectives: WEB LLOs

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Page 1: Charges & Charging · Charges & Charging Electric Charges 1. Describe existence of electrical charges in matter its magnitude, mass, its relative masses, its charges, its quantization

1

Electricity Lecture SeriesElectricity Lecture Series

email: email: [email protected]@salam.uitm.edu.my; ; [email protected]@hotmail.comhttp://http://drjj.uitm.edu.mydrjj.uitm.edu.my

Applied Sciences Education Research Group (ASERG)Faculty of Applied SciencesUniversiti Teknologi MARA

Charges & ChargingCharges & Charging

Electric ChargesElectric Charges

1. Describe existence of electrical charges in matter its magnitude, mass, its relative masses, its charges, its quantization property and its conservation property.

2. Apply the quantization and conservation property for certain charging and discharging process

3. Sketch and explain charging by induction and charging by contact numerically and diagrammatically.

Objectives:

WEB

LLOs

Page 2: Charges & Charging · Charges & Charging Electric Charges 1. Describe existence of electrical charges in matter its magnitude, mass, its relative masses, its charges, its quantization

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Electric ChargesElectric Charges

Experimental Results on Experimental Results on Atomic StructureAtomic StructureMatterMatter: made up of atoms and molecules

Charged objectCharged object: imbalance number of electrons & protonsPositively charged (lost electrons)Negatively charged (gain electrons)

AtomAtom: made up of nucleus, protons and electrons

ConductorsConductors: charges can move freely

InsulatorsInsulators: charges cannot move freely

WEB

LLOs

18.1 18.1 The Origin of ElectricityThe Origin of ElectricityCutnellCutnell & Johnson 7E& Johnson 7E

The electrical nature of matter is inherentin atomic structure.

kg10673.1 27−×=pm

kg10675.1 27−×=nm

kg1011.9 31−×=em

C1060.1 19−×=ecoulombs

How massive is the proton compared to an electron? Use proportional reasoning method to determine the answer.

WEB

LLOs

Page 3: Charges & Charging · Charges & Charging Electric Charges 1. Describe existence of electrical charges in matter its magnitude, mass, its relative masses, its charges, its quantization

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Electric ChargesElectric Charges

Charge quantizationCharge quantization: charges exist in multiples of an elementary charge, the charge of an electron

,..2, eeNeq ==where N are the number of electrons & the elementary charge e is e =1.6 x 10-19 CNumber of charges in 1 C?? N=q/e =1 C/1.6 x 10-19 CN = 6.25 x 1018

Number of charges in 1 μC?? N=q/e =1 μ C/1.6 x 10-19 CN = 6.25 x 10-18

WEB

LLOs

Charges, charging, electrical force & discharging

WEB

LLOs

Page 4: Charges & Charging · Charges & Charging Electric Charges 1. Describe existence of electrical charges in matter its magnitude, mass, its relative masses, its charges, its quantization

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Charges, charging

WEB

LLOs

Charges, charging, electrical force

WEB

LLOs

Page 5: Charges & Charging · Charges & Charging Electric Charges 1. Describe existence of electrical charges in matter its magnitude, mass, its relative masses, its charges, its quantization

5

Charges & charging

WEB

LLOs

Charges, charging, electrical force & discharging

Page 6: Charges & Charging · Charges & Charging Electric Charges 1. Describe existence of electrical charges in matter its magnitude, mass, its relative masses, its charges, its quantization

6

Charges, charging, electrical force & discharging

Charges, charging, electrical force & discharging

Page 7: Charges & Charging · Charges & Charging Electric Charges 1. Describe existence of electrical charges in matter its magnitude, mass, its relative masses, its charges, its quantization

7

Charges, charging, electrical force & discharging

Charges, charging, electrical force & discharging

Page 8: Charges & Charging · Charges & Charging Electric Charges 1. Describe existence of electrical charges in matter its magnitude, mass, its relative masses, its charges, its quantization

8

Charges, charging, electrical force & discharging

Charges, charging, electrical force & discharging

Page 9: Charges & Charging · Charges & Charging Electric Charges 1. Describe existence of electrical charges in matter its magnitude, mass, its relative masses, its charges, its quantization

9

Charges, charging, electrical force & discharging

Charges, charging, electrical force & discharging

Page 10: Charges & Charging · Charges & Charging Electric Charges 1. Describe existence of electrical charges in matter its magnitude, mass, its relative masses, its charges, its quantization

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Charges, charging, electrical force & discharging

18.4 18.4 Charging by ContactCharging by ContactCutnellCutnell & Johnson 7E& Johnson 7E

Charging by contact.

Page 11: Charges & Charging · Charges & Charging Electric Charges 1. Describe existence of electrical charges in matter its magnitude, mass, its relative masses, its charges, its quantization

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18.4 18.4 Charging by InductionCharging by InductionCutnellCutnell & Johnson 7E& Johnson 7E

Charging by induction.

Charges, charging, electrical force & discharging

Page 12: Charges & Charging · Charges & Charging Electric Charges 1. Describe existence of electrical charges in matter its magnitude, mass, its relative masses, its charges, its quantization

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Charges, charging, electrical force & discharging

18.2 18.2 Charged Objects and the Electric ForceCharged Objects and the Electric ForceCutnellCutnell & Johnson 7E& Johnson 7E

LAW OF CONSERVATION OF ELECTRIC CHARGE

During any process, the net electric charge of an isolated system remains constant (is conserved). Total number of negative charges (electrons) and positive charges (protons) must be equal

Page 13: Charges & Charging · Charges & Charging Electric Charges 1. Describe existence of electrical charges in matter its magnitude, mass, its relative masses, its charges, its quantization

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Charge Conservation

A5q

B-3q

A2q

B0q

Aq

Bq

A5q

B-3q

C3q

Shown are conducting spheres each of charges 5q, -3q and 5q

What is the total charge on the spheres?

Sphere A touches sphere B and then separated.

What is the total charge after the process above, the charge on each individual sphere?

Charge Conservation

Bq

C3q

B2q

C2q

Aq

Bq

C3q

Shown are conducting spheres each of charges 5q, -3q and 5q

Sphere B touches sphere C and then separated.

What is the total charge after the process above, the charge on each individual sphere?

What is the total charge on the spheres?

Page 14: Charges & Charging · Charges & Charging Electric Charges 1. Describe existence of electrical charges in matter its magnitude, mass, its relative masses, its charges, its quantization

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18.4 18.4 Charging by Contact and by InductionCharging by Contact and by InductionCutnellCutnell & Johnson 7E& Johnson 7E

The negatively charged rod induces a slight positive surface chargeon the plastic.

Electric Point ChargesElectric Point ChargesElectric forcesElectric forces: Determine forces acting on charge 2

2232 22

reek

rqqkF 23 ==

2

2

2

2

2

2 54rek

rek

rekFF 3 21 2 =+=+

→→

( ) 2

2

2212

44

222

rek

reek

rqqkF 21 ===

→-

+

2r F

q1=2e

q3=2e

What is the magnitude and direction of acceleration of q2?

+ q2=2e

r

up

up

up