Download Series vs. Parallel Circuits

Circuits
DO NOW
• With a partner, collect
– One battery
– One wire
– One lightbulb
• Working with your partner at your desk and
your knowledge of circuits, make the lightbulb
light up.
Hint #1
Hint #2
One side of the wire
in the lightbulb
touches the metal
part of the light
bulb. The other
side of the wire is
connected to the
bottom.
Solution
Series Circuits
You will also have to use Ohm’s Law,
but you can NOT cross contaminate!
Rules
Totals
𝑉𝑇 = 𝐼𝑅𝑒𝑞
Only R1
𝑉1 = 𝐼𝑅1
Only R2
𝑉2 = 𝐼𝑅2
Only R3
𝑉3 = 𝐼𝑅3
If you add a 4th resistor, the total
resistance will INCREASE which
means the total current will
DECREASE. Total voltage is constant
Series Circuits
Rules
1. If the current through R1 is 4 amps,
what is the current through
a. R2?
b. R3?
c. The total current coming out of
the battery?
2. If R1 is 3Ω, R2 is 7Ω, and R3 is 4 Ω, what
is the equivalent resistance of the
circuit?
3. What is the potential drop across
a. R1
b. R2
c. R3
4. What is the total potential difference
supplied by the battery?
Parallel Circuits
You will also have to use Ohm’s Law,
but you can NOT cross contaminate!
Rules
Totals
V= 𝐼𝑇 𝑅𝑒𝑞
Only R1
𝑉 = 𝐼1 𝑅1
Only R2
𝑉 = 𝐼2 𝑅2
Only R3
Req will ALLWAYS be less than the
smallest resistor in the circuit!
V= 𝐼3 𝑅3
If you add a 4th resistor, the total
resistance will DECREASE which
means the total current will
INCREASE. Total voltage is constant
Parallel Circuits
Rules
1. If the potential difference over R1 is 12
volts, what is the potential difference
a. R2?
b. R3?
c. The total potential difference
supplied by the battery?
2. If R1 is 3Ω, R2 is 7Ω, and R3 is 4 Ω, what
is the equivalent resistance of the
circuit?
3. What is the current through
a. R1
b. R2
c. R3
4. What is the total current coming from
the battery?