Download Electric Current

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Electric Current- net movement of electric
charges in a single direction
◦ Example- powering electronics

Electric Circuit- a closed path through which
electrons flow
◦ Electrons flow because of difference in potential
 Example- battery, lightbulb, and wire
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Electrons always flow from where there are
more electrons (high potential) to where there
are fewer electrons (lower potential)
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Battery- a device that maintains the
difference in potential
◦ Supply energy to keep the electrons moving;
doesn’t supply the electrons

Types
◦ Dry-cell (AA battery in remote)
◦ Wet-cell (car battery)
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Cell- consists of one positive electrode and
one negative electrode surrounded by
material called an electrolyte
◦ Electrolyte- a paste that enables charges to move
from one electrode to another
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Wet Cell- Two connected plates (one positive
and one negative) in a liquid conducting
solution (electrolyte)
◦ Several wet cells connected together
◦ Car battery
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Resistance- the tendency for a material to
resist the flow of electrons and convert
electrical energy to other forms of energy
◦ Resistors are used to reduce the flow of a current
through all or part of a circuit
 Help protect more delicate electronic components
 Example- used to computers

Resistors transfer energy into other forms
◦ Light bulb- thermal, light
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Resistance- measured in ohms ()
 All materials have some resistance, even copper wiring
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As temperature increases, resistance
increases
As a material becomes longer (wire),
resistance increases
As material becomes thinner, resistance
increases
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Electric Current- flow of electrons in a single
direction; path of electrons
◦ Measured in Amps (A)- Ammeter
◦ Depends on the amount of electrons that pass
through every second
 1 Amp- 6,250 million electrons per second
◦ Flow from negative voltage to positive voltage
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Voltage Difference- The difference in
potential (the energy of the electrons)
between two different places
◦ Measured in Volts (V)- voltmeter
◦ It’s the pressure that pushes electricity through a
conductor (wire)
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Ohm’s Law- the current in a circuit equals the
voltage difference divided by the resistance
◦ Current (I) measured in Amps
◦ Voltage difference (V) measured in volts
◦ Resistance (R) measured in ohms
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As the resistance increases, the current
decreases
If the voltage difference in a circuit is greater,
the current increases

The voltage difference in a graphing
calculator is 6V, and the resistance is 1,200
. What is the current through the batteries
of the graphing calculator?

The voltage difference in a graphing
calculator is 6V, and the resistance is 1,200
. What is the current through the batteries
of the graphing calculator?
◦ I=V/R
◦ I= 6V/1200 
◦ I= 0.005A

The current through a circuit is 0.0030 A.
What is the resistance of this circuit if the
voltage difference across the circuit is 12V?
◦ I=V/R

The current through a circuit is 0.0030 A.
What is the resistance of this circuit if the
voltage difference across the circuit is 12V?
◦ I=V/R
◦ 0.0030A= 12V/R
◦ R= 4000