Lesson 06 ­ Voltage, Current and Resistance 27mar2014.notebook
March 28, 2014
Current, Voltage and Resistance
Electrical Quanes
Since there are too many electrons moving in a circuit to be counted, sciensts describe large groups of electrons instead of individual ones.
These large groups of electrons are called ___________
1 _________= 6 250 000 000 000 000 000 electrons! Symbol ‐ Q Unit ‐ C (stands for _______)
There are three main quantave measurements that can be recorded from a circuit:
1. Current
Current is the amount of coulombs ___________ by a certain point in a given amount of ___________.
Symbol= Unit= Ex. A circuit that has an amperage of 3 A means that there are 3 coulombs of electrons passing a certain point every second.
I = Q
t
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Lesson 06 ­ Voltage, Current and Resistance 27mar2014.notebook
March 28, 2014
Measuring Current
• The instrument used to measure current is called an ___________________.
• The _________________ must be placed ______________ the circuit in order to measure the numbers of coulombs going by
• It has very lile resistance and does not impede (slow down) the flow of electrons 2. Voltage (Potenal Difference)
Voltage is the amount of ___________ per coulomb of charge.
Symbol= Unit= Ex. A voltage of 3 V means that there are 3J of energy for every Coulomb of electrons in that part of the circuit.
V= E where J is a measure of energy called joules
Q Measuring Voltage
• The instrument used to measure voltage is called a ___________________.
• The _________________ must be placed ______________ two points in the circuit in order to measure the energy difference between these two points. (ie. it is placed ______________ of the circuit)
• It has very high resistance so that electrons flow through the circuit rather than through the meter. 2
Lesson 06 ­ Voltage, Current and Resistance 27mar2014.notebook
March 28, 2014
3. Resistance
Electrical resistance
is a property of a substance that:
1. Hinders the moon of electrons moving through
the circuit.
2. Causes joules of electrical energy to be converted
into other forms of energy such as _________ or ___________.
Ex. filament light bulb‐ Symbol= Unit=
Review
1. Complete the following chart using your notes:
Term
Charge
Symbol for Term
Unit
Unit Symbol
Q
Coulombs C
Energy Current
Resistance
Voltage
2. Describe what happens to the energy of the "coulomb" as it moves through an entire loop of the circuit? Specifically, explain what happens as it moves through the power source and the load.
.
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Lesson 06 ­ Voltage, Current and Resistance 27mar2014.notebook
March 28, 2014
Current, Voltage, and Resistance Homework Sheet
1.
2.
How much current is there in a circuit if there are 10 Coulombs of electrons moving past an ammeter in 2 seconds me?
300 C of charge pass a point in a copper wire in 25s. Determine the current at that point in the circuit.
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Lesson 06 ­ Voltage, Current and Resistance 27mar2014.notebook
3.
Complete the following:
1 Amp = 1 Coulomb
5 Amps = __ Coulomb(s)
8 Amps = ___ Coulombs
1 second
___ second(s)
___ second(s)
4.
March 28, 2014
Voltage is the amount of energy per coulomb of charge. Voltage is measured in Volts. What is 1 volt equal to?
1.
Complete the following:
1 Volt = 1 Joule 1 Coulomb
8 Volts = __ Joule(s)
___ Coulomb(s)
12 Volts= ___ Joule(s)
___ Coulomb(s)
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Lesson 06 ­ Voltage, Current and Resistance 27mar2014.notebook
March 28, 2014
In a baery, 8C of charge picks up 72J of energy as it passes from the posive terminal through the baery to the negave terminal. What is the voltage (Potenal Difference) 6.
of the baery?
7.
Why are voltmeters placed outside of the circuit rather than within the circuit? If a voltmeter was placed within a circuit what effect would it have on the circuit?
8.
Explain in your own words how resistance affects current (think of the box analogy from class)
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