1. Ohm’s Law Power Electric Energy Electric Cost
October 9, 2017
Ohm’s Law
Power
Electric Energy
Electric Cost

2. Drill – Take out Drills and Classwork from last week
A m-long copper wire of radius 0.15 mm is connected across a 1.5-V battery. The resistivity of copper is 1.68 x 10-8 m.
Calculate the resistance of the wire.
Calculate the current passing through it.
The wires in a home carry 13 A of current. The voltage drop across the wires because of their resistance should be 1.0 V or less. If the wires are made of aluminum and have a radius of 1.4 mm, what is their maximum length? The resistivity of aluminum is 2.8 x 10-8 m.

3. Review of Ohm’s Law + Electric Cost Quiz
October 10, 2017
Review of Ohm’s Law + Electric Cost Quiz

4. Drill – Complete the Worksheet SILENTLY

5. Explanations Explain the relationships found in Ohm’s Law:
Voltage vs. Current
Current vs. Resistance
Draw the graph of voltage vs. current.
What does the slope of a voltage vs. current graph represent. What unit does the slope have? Explain.

6. Calculations Equations (I will write on the board during quiz)
R = pL/A
R = R[1 +⍺ΔT]
R = V/I
I = Q/t
P = IV
E = Pt
Cost = (E)(cost/kWh)

7. Calculations Units (You must memorize!) Resistance (R) = Ω
Resistivity (𝘱) = Ω*m
Voltage (V) = V
Current (I) = A
Charge (Q) = C
Power (P) = W
Energy (E) = kWh
Cost = $

8. Practice Calculations