October 24 • Set up a New Notes Page

• Tuesday Bellwork

• Homework:

• Continue to study/review Ch 19 if needed

• Read Ch 20 and study the vocab

Notes II Chapter 20 Section 1

Circuit: a closed path through which charge

can flow

• Made of low resistance material (a conductor) • Designed to do specific jobs

Closed Circuits

• loop is complete

• Current can flow

Open Circuits

• loop is incomplete

• Current cannot flow

https://socratic.org/questions/what-is-the-difference-between-an-open-and-closed-circuit

Batteries have connections at both ends so

charge can follow a closed path to and from

the battery.

By Marekich (Own work) [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

The cords we use everyday are not a one way street. They are actually a looped circuit

Parts of a Circuit • Voltage Source • Conductor • Switch • Electrical Device

(Resistor)

Voltage Source (battery)

Conductor (wire)

Switch

Electrical device (bulb)

https://www.ck12.org/physics/circuit/lesson/Electric-Circuits-MS-PS/

Voltage Source: provides the electric

potential for charge to flow

• Example: battery, power plant

• Voltage “pushes” electrons through a

circuit (like water pressure)

http://cdn.wonderfulengineering.com/wp-content/uploads/2014/06/What-is-a-resistor-10.jpg

Resistor: An electrical device that slows the flow of

charge in a circuit

When you turn down the volume on your TV or stereo… • You’re actually turning up the resistance • Electric current to loudspeaker is reduced

Some tech savvy parents add resistors to the wiring of children's toys to make them less noisy

Short Circuit: An unintended and undesired

path connecting one part of a circuit with

another

• still a closed circuit

http://johnjbolla.weebly.com/circuits.html

Current follows the path of least resistance. The

path isn’t always the one we want…

• Humans can become part of the path

• Can cause materials to overheat or start on fire

By Robert Lawton - Own work, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=991415

Ch 20 Notes I Vocab Page (on the back)

Drawing Circuit Diagrams

Drawing Circuit Diagrams

Battery

2 Cell Battery

Open switch

Closed switch

Drawing Circuit Diagrams

Resistor

Motor

Fan

Speaker

Drawing Circuit Diagrams

Light Bulb LED

Wire

Chapter 20 Section 2 Notes II

Circuits make Electric Current Useful

Series Circuits Parallel Circuits

Series Circuit: a circuit in which

current follows a single path.

Each device that is wired shares a

path to and from the voltage

source.

Series Circuit: a circuit in which current follows a single

path.

Advantage:

• Minimal wire needed

• Voltage sources in series add together

Disadvantage:

• If one part “burns out” the entire circuit is broken

• Voltage is shared by components

Voltage is shared

The more lights there are the

dimmer they will be

If we take away a light the

other two will become

brighter

Parallel Circuit: a circuit in

which current follows more

than one path.

Each device that is wired has

its own path to and from the

voltage source.

Parallel Circuit: a circuit in which current follows more than

one path.

Advantage:

• Voltage remains the same throughout (all lights can be

bright no matter how many)

• If one burns out, the rest still function

Disadvantage:

• Cant add up voltage

• Uses more wiring

Is it Series or Parallel?

Parallel

Series

Series

Series

Parallel

Both!

Parallel

Series

Very short Series vs parallel video clip https://www.youtube.com/watch?v=RQ3djos_LY8

https://energy.gov/articles/how-do-holiday-lights-work

Are these lights in series or parallel?

Are these lights in series or parallel?