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Physics. Chapter 20: Circuits and Circuit Elements. Circuits and Circuit Elements. Schematic Diagram of an Electric Circuit Uses Symbols to Represent Elements within the Circuit. R 2. R 1. +. -. Circuits and Circuit Elements. Schematics Some Standard Symbols Conductor Switch Fuse. - PowerPoint PPT Presentation
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Circuits and Circuit Elements
SchematicDiagram of an Electric CircuitUses Symbols to Represent Elements within
the Circuit
+ -
R1R2
Circuits and Circuit Elements
Series WiringMore than One Device Connected to a Voltage
SourceProvides the Same Electric Current Through
Each Device
Circuits and Circuit Elements
Series WiringCurrent Flow Interrupted at One Device Will
Prevent Current from Reaching the Other Device
+ -
R1R2
I
Circuits and Circuit Elements
Series WiringThe Voltage Supplied by the Power Source is
Divided Among the Devices Used in the Circuit
+ -
R1R2
I
V1V2...21 VVV
Circuits and Circuit Elements
Series WiringThe Resistance to the Circuit Voltage is the
Sum of the Device ResistanceEquivalent Resistance in Series (Rs)
+ -
R1R2
I
V1V2...21 RRRs
Circuits and Circuit Elements
Parallel WiringMore than One Device Connected to a Voltage
SourceProvides the Same Electric Voltage Through
Each Device
Circuits and Circuit Elements
Parallel WiringCurrent Flow Interrupted at One Device Will
NOT Prevent Current from Reaching the Other Device
+ -
R1
R2
I1
I2
I
Circuits and Circuit Elements
Parallel WiringVoltage is the Same at Each ResistorCurrent is Divided Among the Devices Present
in the Circuit
+ -
R1
R2
I1
I2
I
Circuits and Circuit Elements
Parallel WiringSince I=V/R and
Voltage is Constant
...111
21 RRRp
+ -
R1
R2
I1
I2
I
...21 III
Circuits and Circuit Elements
Parallel WiringRp – Equivalent Resistance in Parallel
+ -
R1
R2
I1
I2
I
...21 III
...111
21 RRRp
Circuits and Circuit Elements
Problem: A current of 1.2 A is measured through a light
bulb when it is connected across a 120V source. What power is dissipated by the bulb?
Circuits and Circuit Elements
Problem: A 12V automobile battery is connected to an
electric starter motor. The current through the motor is 210A. How many joules of energy does the battery deliver to the motor each second, and what power, in watts, does the motor use?
Circuits and Circuit Elements
Problem: A flashlight bulb is connected across a 3.0V
potential difference. The current through the lamp is 1.5A. What is the power rating of the lamp, and how much electric energy does the lamp use in 11 minutes?
Circuits and Circuit Elements
Solution: V = 3.0V I = 1.5 A P = ?
WAVVIP 5.4)5.1)(0.3(
Jxs
WPtEsot
EP 31097.2
min1
60
1
min11)5.4(,
Circuits and Circuit Elements
Problem: What voltage is applied to a 4.0 resistor if the
current is 1.5 A?
Circuits and Circuit Elements
Problem: A voltage of 75V is placed across a 15
resistor. What is the current through the resistor?
Circuits and Circuit Elements
Problem: The graph in shows
the current through a device called a silicon diode. A potential difference of +0.70 V is placed across the diode. What resistance would be calculated?
Circuits and Circuit Elements
Problem: Draw a series circuit diagram to include a
16 resistor, a battery, and an ammeter that reads 1.75 A. Conventional current is measured through the meter from left to right. Indicate the positive terminal and the voltage of the battery.
Circuits and Circuit Elements
Problem: The wire in a house circuit is rated at 15.0 A
and has a resistance of 0.15 . What is its power rating?
Circuits and Circuit Elements
Problem: An electric motor operates a pump that
irrigates a farmer’s crop by pumping 10,000 L of water a vertical distance of 8.0 m into a field each hour. The motor has an operating resistance of 22.0 and is connected across a 110V source. What current does it draw, and how efficient is the motor?
Circuits and Circuit Elements
Solution: V = 110VR = 22.0 I = 5.0A
JxmsmkgxmgdEw524 108.7)0.8)(/8.9)(101(
JxsVAIVtEm61098.1)3600)(110)(0.5(
%391001098.1
108.7100
6
5
xJx
Jxx
E
EEff
m
w
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