Download What is a Scientist? - Cockeysville Middle School

OHM’S LAW
Objective: To use Ohm’s Law relationships to
determine voltage, current, and
resistance in simple circuits.
Energy Note: How are current voltage, and resistance
related ?
Drill:
1. Get a new lab from the SET.
2. Complete Activity 1, #1 only.
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OHM’S LAW
Current (I) : the continuous flow of electrons
through a circuit units: amperes (A)
Voltage (V): the force causing the flow of
electrons
units: volts (V)
Resistance (R): anything that hinders the flow
of electrons (current) units: ohms (Ω)
HANDOUT
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OHM’S LAW
Ohm’s Law provides the relationship between
current, voltage and resistance.
Ohm’s Law → Voltage = Current × Resistance
Work with your neighbor to rewrite the Ohm’s
Law formula in terms of the other 2 variables.
Resistance = Voltage ÷ Current
Current = Voltage ÷ Resistance
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Activity 3: Applying the Formulas
A 12 volt circuit is used to operate a light. The
resistance in the circuit is 2.5 Ω. What is the
current going through the circuit?
Current = Voltage ÷ Resistance
Current = 12V ÷ 2.5Ω
Current = 4.8A
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Activity 3: Applying the Formulas
What is the voltage (electrical pressure) of a
circuit with a current of 8.75 amps and a
resistance of 9 Ω?
Voltage = Current × Resistance
Voltage = 8.75A × 9Ω
Voltage = 78.75V
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OHM’S LAW
Explain what happens to the current in a
circuit that obeys Ohm’s Law if the
resistance is doubled and the voltage
remains the same.
ELMO DEMO
TRY THIS: Explain what happens to
current in a circuit if voltage is tripled and
resistance is cut in half.
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HOMEWORK:
Ohm’s Law Practice Problem
Sheet. Show all work.
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