Transcript Electrical Current

Mr. Fleming
D4. Explain the relationship among voltage,
current and resistance in a simple series
circuit.
What are the factors that affect how electrons
move along a wire?
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Static electricity:
electricity involving a
build-up of stationary
charges.
Current electricity:
electricity involving the
flow of e- through a
conductive material.
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Voltage, current and resistance are all related
to each other by a formula called Ohm’s Law,
developed by George Simon Ohm in 1827.
Current = Volts/ Resistance
I= V/R
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Current: rate at which electrons move past a
point in a wire.
Measured by using amperes or amps (A)
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Voltage: the difference in electrical potential
between two points.
Measured by using Volts (V)
Voltage provides the force or push that
moves electrons through a wire.
An increase in voltage causes an increase in
electron flow or current.
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Resistance - opposition of a substance to a
flow of electrons.
Measured by using Ohms (Ω)
The higher the resistance; the lower the
current.
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Material
◦ Conductors decrease resistance.
◦ Insulators increase resistance.
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Thickness of a wire
◦ As thickness increases, resistance decreases.
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Length of a wire
◦ As length increases, so does resistance
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Temperature
◦ As the temperature increases, so does resistance.
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Power is a function of Voltage and current
expressed by the equation.
P=IxV
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Power: The rate at which energy is transferred
or used in an electrical circuit.
Measured by using Watts (W)
Steps to solving Word Problems:
1. Read the problem
2. List all known values with their
units
3. Write out equation with unknown
isolated
4. Plug in #’s with units
5. Solve, give answer with PROPER
UNIT!
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Current = Volts/ Resistance
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I= V/R
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Power is a function of Voltage and current
expressed by the equation.
P=IxV
What is the current
passing through a 3 W
resistance that is
connected to a
12
volt battery?
12 volts/3 ohms= 4 amps
A 30 amp current is
passing through a 4 W
resistor, what is the
voltage in the circuit?
30 amps x 4 ohms= 120 volts
A 6 v battery pushes
electrons through a
circuit with a current of
0.3 amps, what is the
resistance of this circuit?
6 volts/ 0.30 amps= 20 ohms
A 12 v battery causes a 0.3 amp
current to pass through a bulb.
A) What is the bulb’s power
usage?
B) What is the resistance of the
bulb?
A.
12 volts x 0.3 amps= 3.6 watts
B.
12 volts/ 0.3 amps= 40 ohms
A.) How much current passes
through a 40 W bulb
attached to a 120 v power
source?
B.) What is the resistance of
the bulb?
A.
40 watts/ 120 volts= 0.33 amps
B.
120 volts/0.33 amps= 363 ohms
A. A 100 W bulb has a 0.2
amp current passing
through it, what is the
voltage of the power
source?
B. What is the resistance of
the bulb?
A.
100 watts/ 0.20 amps= 500 volts
B.
500 volts/0.20 amps= 2500 ohms
Name 2 factors or things that affect current?
Voltage and Resistance
How are resistance and current related to each
other?
Amps= Volts/ Ohms
Ohms= Volts/Amps