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Parallel Circuits
Thursday, April 18, 2015
Unit 9: Electricity
Thursday, 2/18
 Respond to the following on your warm-up sheet.
What happens to the current as it moves through the circuit? Support
your answer.
Upcoming dates
 Tuesday, 2/16 – Series circuit quiz – moved to Thursday, 2/18
 Thursday, 2/17 – Parallel circuit quiz – moved to Monday, 2/22
 Monday, 2/22 – Circuit design due
 Wednesday, 2/24 – Unit quiz - moved to Friday moved to Friday, 2/26
 Friday, 2/26 – Electricity Test and last day to turn in unit missing work –
moved to Tuesday, 3/1
 Thursday, 3/3 – Magnetism quiz – moved to Monday, 3/7
 Friday, 3/4 – 3NWS Extra credit due by 4:00 PM
Unit Overview
Types of Electricity
Dynamic
Direct Current
(DC)
Series
Static
Alternating
Current (AC)
Parallel
Complex
Circuit – In Series
 Only one path
Circuit – In Parallel
 More than one path
What do you think?
 If a circuit has multiple branches will the voltage,
resistance, and current behave differently? Write your
thoughts in your notes.
Parallel
1. reciprocal of the total resistance is the
sum of the reciprocals of the separate
resistors
1/RT = 1/R1 + 1/R2 +1/R3 + ...
2. total current is the sum of the current
through each resistor
IT = I1 + I2 + I3 + ...
3. potential difference is the same across
each resistor
VT = V1 = V2 = V3 = ...
In other words, in a parallel circuit,
resistance adds as reciprocals,
voltage stays the same, and current splits.
Kirchhoff’s Rules
Junction Rule: the sum of all currents entering the
junction must equal the sum of all currents leaving
the junction.
See link on my webpage for detailed
instructions on how to solve
Practice