Series Circuits Notes

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CHAPTER 8ACHAPTER 8A

SeriesSeries

CircuitsCircuits


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8.1: DEFINITIONSA) Current:

Flows from to +

It is the flow of ELECTRONS!

B) Circuit:

y Where current flows

2


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y Circuitwith only1 loop.

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Power pack -->

Resistor -->


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Gives the push needed to make the current flow.

Made up of1 cell or more cells (battery).

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ii) The Battery:

i) The Cell:

Symbols:

Elements of the Circuit

The Power Supply:

Big line +Little line -


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The Resistor:

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Symbols:

i) Resistor

ii) Light Bulb

Resists the flow of current

Changes electrical energy into heat, light, soundand or motion. (Light Bulbs, Motors, Speakers)


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E) The Switch:

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Closed, current flows Open, current does not flow

(like a draw bridge)

Symbol:


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A) Ammeter:

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Measures the current flowing through thecircuit

Always connected in the circuit In circuit = in series

Symbol: A

8.3: MEASURING INSTRUMENTS


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Examples: Connect the ammeters.

8

A

A

A

AT= A1 = A2 = A3 =


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y Measures the potential difference between 2points, that is,byhowmuch the push haschanged

yAlways connected outside the circuity Outside circuit = in parallel

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Symbol: V

Voltmeter:


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Example: Connect the voltmeter

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V V

V


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Label:

The Vs

The Is

The Rs

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R1

R2

R3

IT I1

I3

Hand-out: Exercise Booklet #1

8.4: SETTING UP THE CIRCUIT


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A) Resistance:

Variable: R

Unit: Ohm Opposite ofconductance G

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R = 1G

8.5: THE MATH QUANTITIES


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German physicist who developed themathematical relationship between the current,

voltage and resistance in a circuit, a.k.a. OhmsLaw.

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Georg Simon Ohm

(1787 - 1854)


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Variable: G Unit: Siemens S Opposite of resistance

G = 1R

B) Conductance:


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ErnstWerner Von Siemens

(1816-1892)

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German inventor who developed the electromagnet.


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yVariable: V

y Unit: Volt V

y Changesacross the resistors

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VT= V1 + V2 + V3 +

C) Voltage:


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Alessandro Giuseppe Antonio Anastasio Volta(1745 - 1827)

Italian inventor who invented the first battery.


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yVariable: I

y Unit: Ampere or amp A

y Same everywhere

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IT= I1 = I2 = I3 =

D) Intensity of the Current:


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Andr-Marie Ampre

(1775 - 1836)

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French mathematician who discovered the laws ofelectromagnetism.


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8.6: OHMS LAW

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V = RI

Thou Shalt Remember it !

V1 = R1 I1

V2 = R2 I2V3 = R3 I3VT = RT IT


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Example: Find everything

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VT= ?

IT= 2A

R1 = 10

Answers:I1 = 2A

V1 = 20VVT= 20V

Hand-out: Exercise Booklet #2


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y Its the single resistor that representsall the resistors.

(If you could combine all the resistors into one)

For Series Circuits ONLY:

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RT

= R1+R

2+

8.7: EQUIVALENT OR TOTAL RESISTANCE RT


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Example #1: Find IT

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VT

= 20 V

R1 = 2

R2

= 3

R3 = 5


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Example #2: Find everything

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R1 = 4

R2

= ?

R3 = 3

VT= 10V

IT= 1A


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R1 = ?

R2 = ?

R3 = ?

VT= 180VIT= 3A

Example #3: Find everything

The resistors are identical


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A) Resistance:

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V(V)

I(A)

R = V

I

8.8: GRAPHS


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Examples: Find R.

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a) V(V)

I( )

20

5

V = R I

20 = R 5

@ R = 4


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B) Conductance:

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G = 1

R

I(A)

V(V)


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Example #1: Find G.

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I( )

( )

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0.5

G = IV

G = 300.5

@G = 60 S

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Series Circuits Notes