A GENDA – M AY 7

Talk about review

Finish Ch 22 notes

Ch 23 notes

Virtual lab

Monday: Ch 22 and 23 bkwk due and virtual lab
due. Take test if not here Wednesday.
C H . 23
E LECTRIC C IRCUITS

Create a circuit with 1 battery and 1 light

Create a circuit with 2 batteries and 1 light

Create a circuit with 2 batteries and 2 lights
connected in series

Create a circuit with 2 batteries and two lights in
parallel

Create a circuit with 2 batteries and 1 light
parallel with 2 in series
S ERIES C IRCUITS

A series circuit is a circuit in which all of the
current travels through each device
S ERIES C IRCUITS

Voltage drops / potential difference

The potential difference of the generator is equal
to the potential difference across each resistor
(lamp)
Vsource  VA  VB
S ERIES C IRCUITS

Resistance in the circuit is equal to sum of the
resistances in each component
R  RA  RB  ...
S ERIES C IRCUITS

Current in the circuit is equal to the potential
difference in the whole circuit divided by the
resistance of all of the components
Vsource
I
R
E XAMPLE

Three 20Ω resistors are connected in series
across a 120 V generator. What is the equivalent
resistance of the circuit? What is the current in
the circuit?
PARALLEL C IRCUITS

A circuit with several current paths
PARALLEL C IRCUITS

The voltage through each path is the same

The current can be found through each individual path

The total current is that of all of the paths combined
A
120 V
24Ω
6Ω
120 V
120 V
9Ω
120 V
PARALLEL C IRCUITS

The resistance for the whole parallel circuit will
be less than each resistor because each resistor
offers an additional path for the current

Equation for finding the total resistance of a
parallel circuit
1
1
1


 ...
R RA RB
E XAMPLE

A 120Ω resistor, a 60Ω resistor, and a 40Ω resistor
are connected in parallel and placed across a 12
V battery.

What is the equivalent resistance of the parallel
circuit?

What is the current through the entire circuit?

What is the current through each branch?
23.2
S AFETY D EVICES

Fuse –


A short piece of metal that melts when the
current traveling through it is too large
Short Circuit –

When there is very low resistance in a circuit.
This can easily cause fires if there is no fuse or
circuit breaker to stop the high levels of current
E XAMPLE

Two 60Ω resistors are connected in parallel. This parallel arrangement is
connected in series with a 30Ω resistor. The combination is then placed
across a 120V battery.

Draw a diagram of the circuit.

What is the equivalent resistance of the parallel portion?

What single resistance could replace the three original resistors?

What is the current in the circuit?

What is the voltage drop across the 30Ω resistor?

What is the voltage drop across the parallel portion of the circuit?

What is the current in each branch of the parallel portion of the circuit?
B KWK

P550: 1, 4, 7, 8, 15, 21, 24, 28, 32