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

Drill – Take out Drills and Classwork from last week A 120.0-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.

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

Drill – Complete the Worksheet SILENTLY

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.

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)

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 = $

Practice Calculations