Download Lesson 4

Lesson Plan – Relating Current, Voltage, and Resistance
Curriculum Expectations:
-
E2.7: investigate the quantitative relationships between current, potential difference, and
resistance in a simple series circuit
E2.8: solve simple problems involving potential difference V, electric current I, and resistance R,
using the quantitative relationship V = IR
E3.6: describe, qualitatively, the interrelationships between resistance, potential difference, and
electric current (e.g., the effect on current when potential difference is changed and resistance
is constant)
Lesson
Relationship between voltage and current on graph (R=V/I)  Ohm’s Law
-
Georg Ohm (1787-1854)
Graphed voltage vs current, resulted in a linear relationship
Solve sample problems 1-3
Lesson Plan – How Series and Parallel Circuits Differ
Curriculum Expectations:
-
E2.7: investigate the quantitative relationships between current, potential difference, and
resistance in a simple series circuit
E2.8: solve simple problems involving potential difference V, electric current I, and resistance R,
using the quantitative relationship V = IR
E3.6: describe, qualitatively, the interrelationships between resistance, potential difference, and
electric current (e.g., the effect on current when potential difference is changed and resistance
is constant)
Lesson
Review/restate Kirchoff’s Current & Voltage Laws
-
-
Current through loads in series
o More resistance with increased loads
o Current in a series circuit is the same throughout
Current through loads in parallel
o Current going into a junction = current coming out
Voltage through loads in series
o Vload = Vsource / # of loads
Voltage through loads in parallel
o Voltage drop across each parallel load is the same as the voltage drop across battery
Solve Sample Problems 1-4
Summary table of resistance, current, and voltage in circuits
Quantity
Total resistance of circuit (RT)
Current through loads (Iload)
Series Circuits
Increases
Isource decreases as more loads
are added
Voltage across loads (Vload)
Vsource splits based on the
number of loads
Parallel Circuits
Decreases
Isource splits among loads based
on the number of branches in
parallel
Voltage of each parallel branch
is the same as Vsource