Circuits & Batteries

Review … Current electricity is the steady flow of electrons

An electric circuit is a continuous path along which electrons flow from one end of a battery to another. -

Electrons are negatively  charged, and are attracted to the positive end of a battery and repelled by the negative end.

So when the battery is hooked up to something that lets the electrons flow through it, they flow from negative to positive.

Electric circuits must always have at least: ● an energy source for electrons ● a conductor for electrons to travel through ● a load that converts electrical energy into a more useful form energy

A basic electric circuit

Add-ons to electric circuits: ● a switch allows you to safely stop or allow the flow of electricity

OFF open circuit, ON closed circuit Which switch is ON? OFF open circuit, electrons cannot flow ON closed circuit electrons can flow

OPEN CIRCUIT CLOSED CIRCUIT

Electrochemical Cells

An electrochemical cell is a device that converts chemical energy (from chemical reactions) into electrical energy

Parts of an Electrochemical Cells A. Electrolyte - liquid that conducts electricity and where electrons are released B. Negative Electrode – the end where newly charged electrons are collected and enters the circuit C. Positive Electrode - the end where used electrons from the circuit are returned to the battery

Positive + Electrode Negative - Electrode

DIY Electrochemical Cell grapefruit What is the kind of electrolyte used in this battery? Grapefruit Juice (citric acid)

Which electrode gains electrons from the circuit? DIY Electrochemical Cell grapefruit Which electrode gains electrons from the circuit? Copper Electrode (+)

Which electrode loses electrons from the circuit? DIY Electrochemical Cell grapefruit Which electrode loses electrons from the circuit? Zinc Electrode (-)

Another DIY Electrochemical Cell

Battery Hacks https://www.youtube.com/watch?v=ZpD0NjMPT8w

2 Types of Electrochemical Cells Wet Cells – contain an electrolyte liquid Rechargeable Ex: car batteries, phone batteries Dry Cells – contains an electrolyte paste Doesn’t leak as much, smaller, more portable BUT the chemicals tend to get used up and charges can no longer be separated; non-rechargable Ex: AA batteries, watch batteries

How Do Batteries Work? https://www.youtube.com/watch?v=9OVtk6G2TnQ

Always recycle batteries as they contain toxic heavy metals such as nickel, cadmium, and lead 50% of all of the toxic metals in landfills comes from batteries!

Recycling Batteries Public Service Announcement https://www.youtube.com/watch?v=8cTjPBA3wrA

1 Read pages 432-436 pg 436 #1-5