Download CURRENT, VOLTAGE, RESISTANCE Current

Name: _________________________________
Date: _________________________
SNC1D
CURRENT, VOLTAGE, RESISTANCE
Current
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The _____________________ is the movement of the electrons
It measures the amount of charge that passes a single point in a wire in every second
An _________________________ is a device that is used to measure the amount of
electric current flowing through a wire—it needs to be connected __________________
the circuit to be able to measure the current
The unit of current is _____________________ (A)
Voltage
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The __________________ (V) measures two things: 1) the electrical potential energy 2)
the electrical potential difference
_________________________________: the energy that is given to the electrons in the
battery (or other source)—this is the energy that is stored
As electrons move through the circuit, they will give/lose some energy to the load—the
amount of energy that the electrons give to the load is called the
________________________________________
A __________________ is a device that measures the electric potential difference at
different parts of the circuit—a voltmeter needs to be connected OUTSIDE of the circuit
in order to measure the voltages
The unit of voltage is volts (V)
Resistance
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Resistance is the ability of a material to slow down the flow of electric current
The unit of resistance is the ______________ (Ω) and the device that measures
resistance is called an ohmmeter—the ohmmeter also has to be connected on the
___________________ of the circuit.
A multimeter is a device that can measure current, voltage and resistance by changing
the settings on the machine
A _____________________ is a device especially designed to reduce the flow of the
current
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Name: _________________________________
Date: _________________________
SNC1D
Factors that Affect Resistance
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All materials have some internal resistance
The bigger the resistance, the lower the current and the slower the electrons move. As
the electrons move through the circuit, they bump into the atoms of the materials. This
causes heat to be released. So the higher the resistance, the more the electrons are
bumping into the material and the more it heats up.
Internal resistance depends on a few factors:
1. Type of Material
o Some materials allow electrons to move more freely than others
o Copper is an excellent conductor and has low resistance
o ____________________ is even better than copper but is more
expensive
2. Cross-Sectional Area
o The diameter of the cross-section gives you an idea how thick the
wire is
o The __________________ the diameter of the cross-section, the
less resistance there is—this is because, in wider wires the
electrons have more room to move freely
3. Length
o When the wire is longer, the electrons have a greater distance to
travel and so the resistance ____________________.
4. Temperature
o When the wire is warmer, the wire gains energy and starts to
vibrate.
o As the wire vibrates, the electrons in the current are more likely
to bump into the atoms of the wire—so as the temperature
increases, the resistance increases
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