1. ONACD - Editable curriculum designed for teachers by teachers
Series Circuits
One after another
ONACD –Editable Curriculum designed for teachers by teachers
http://www.allaboutcircuits.com/vol_1/chpt_5/2.html
2. ONACD - Editable curriculum designed for teachers by teachers
Series
For electrical circuits the term “series” indicates that
components are connected in a way such that current
flows in and then out of each component before going
on to the next component. If household plumbing was
like this you would have to be very carful what order you
installed your faucets!
If voltage is supplied at a constant value, as it typically is,
the following observations for current and total
resistance can be made:
3. ONACD - Editable curriculum designed for teachers by teachers
Current
The value of current at any point in the circuit will be
constant for a series circuit.
There is only one path for the current as it goes through
the circuit. Consequently, if there is a break in the circuit
the flow of charges stops for the entire circuit.
This plagued older Christmas lights when a bulb would
burn out. A newer design causes burned out bulbs to
fuse a wire and thus the charges keep flowing and the
rest of the bulbs stay lit.
In a series circuit current is calculated using total voltage
and total resistance with the formula V=IR.
4. ONACD - Editable curriculum designed for teachers by teachers
Total Resistance
The addition of more resistors into a series circuit
increases the total resistance.
Each resistor causes a unique drop in the voltage
based on its resistance. Resistance converts electrical
energy into heat. So each added resistor reduces the
amount of current that can flow. Too much resistance
on one path will stop the current all together.
In a series circuit total resistance is calculated by
adding the resistors together with a formula like:
RT=R1+R2+R3+…
Where RT is resistance total and R1,R2,R3,… are the
resistance of each resistor.
5. ONACD - Editable curriculum designed for teachers by teachers
Sample Calculations
Consider the following series circuit with two identical
resistors.
1.What is the total:
a. voltage? 12V
b. resistance? RT = R1+R2
RT = 2+2
RT = 4Ω
c. current?
V = IR
12 = I(4)
12/4 = I
3A = I
6. ONACD - Editable curriculum designed for teachers by teachers
1. What is the current
a) at A?
3A
b) at B?
3A
c)at C?
3A
7. ONACD - Editable curriculum designed for teachers by teachers
3.What is the Voltage across:
a. A to C?
12V
b. A to B?
V = IR
V = (3)(2)
V = 6V
c. B to C?
Same resistance so 6V
