electric currents (r)
DESCRIPTION
Electric Currents (R). Resistors (L). circuit symbol. what is the resistance of this resistor?. Try some others. Electric Power (L). Power = Energy / time. Other useful forms:. Think-Pair-Share (L). - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Electric Currents (R)](https://reader036.vdocuments.net/reader036/viewer/2022062411/56816860550346895ddeaed2/html5/thumbnails/1.jpg)
General Physics 2 Current & Resistance 1
Electric Currents (R)
![Page 2: Electric Currents (R)](https://reader036.vdocuments.net/reader036/viewer/2022062411/56816860550346895ddeaed2/html5/thumbnails/2.jpg)
General Physics 2 Current & Resistance 2
Resistors (L)
circuit symbol
what is the resistance of this resistor? Try some others.
![Page 3: Electric Currents (R)](https://reader036.vdocuments.net/reader036/viewer/2022062411/56816860550346895ddeaed2/html5/thumbnails/3.jpg)
General Physics 2 Current & Resistance 3
Electric Power (L)
• Power = Energy / time
Other usefulforms:
![Page 4: Electric Currents (R)](https://reader036.vdocuments.net/reader036/viewer/2022062411/56816860550346895ddeaed2/html5/thumbnails/4.jpg)
General Physics 2 Current & Resistance 4
Think-Pair-Share (L)
• You buy a 75-W lightbulb in Europe, where electricity is delivered to homes at 240 V. If you use the lightbulb in the US at 120 V (assume its resistance does not change), how bright will it be relative to 75-W 120-V bulbs? [Hint: assume that brightness is proportional to power consumed.]
![Page 5: Electric Currents (R)](https://reader036.vdocuments.net/reader036/viewer/2022062411/56816860550346895ddeaed2/html5/thumbnails/5.jpg)
General Physics 2 Current & Resistance 5
Think-Pair-Share (L)
• How many kWh of energy does a 550-W toaster use in the morning if it is in operation for a total of 15 min? At a cost of 9.0 cents/kWh, estimate how much this would add to your monthly electric bill if you made toast four mornings per week.
![Page 6: Electric Currents (R)](https://reader036.vdocuments.net/reader036/viewer/2022062411/56816860550346895ddeaed2/html5/thumbnails/6.jpg)
General Physics 2 Current & Resistance 6
Power in Household Circuits (L)
• Wires heat up at a rate equal to I2R (power)• fire hazard if I is too large• fuses prevent overloads by breaking circuit• short - two wires touching
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General Physics 2 Current & Resistance 7
Fuses (L)
fuses that need tobe replaced
circuit breaker- breaks circuitwith a switch
![Page 8: Electric Currents (R)](https://reader036.vdocuments.net/reader036/viewer/2022062411/56816860550346895ddeaed2/html5/thumbnails/8.jpg)
General Physics 2 Current & Resistance 8
Household Circuits (L)
• What is the total current draw by these devices? If the circuit has a 20-A fuse, will the fuse blow?
![Page 9: Electric Currents (R)](https://reader036.vdocuments.net/reader036/viewer/2022062411/56816860550346895ddeaed2/html5/thumbnails/9.jpg)
General Physics 2 Current & Resistance 9
Alternating Current (L)
• DC • direct current• current is constant
• AC• alternating current• current varies like a sine wave• frequency usually 60 Hz (60
cycles per second)• Equations are valid when you
use RMS values
![Page 10: Electric Currents (R)](https://reader036.vdocuments.net/reader036/viewer/2022062411/56816860550346895ddeaed2/html5/thumbnails/10.jpg)
General Physics 2 Current & Resistance 10
Human Nervous System (L)
Messagestransmitted within nervous system are electrical signals passingalong the neuron
![Page 11: Electric Currents (R)](https://reader036.vdocuments.net/reader036/viewer/2022062411/56816860550346895ddeaed2/html5/thumbnails/11.jpg)
General Physics 2 Circuits 11
Practice Problems
• Determine the equivalent resistance and the current through R1 for the circuits shown. Assume R1 = 10, R2 = 20 , and R1 = 30 , and the battery is 12 V.