Download Electric Potential Energy

Physics Unit
Chapter 8 – pages 268 – 303
Chapter 8
Section 8.1 Electric Potential Energy and Voltage
Electric Charge
How can we separate electric charges?
Recall in Chapter 7
We separated charges by rubbing objects together
 friction
Unlike charges want to come back together 
opposite charges attract
The further we move unlike charges apart, the
more electric potential energy they gain.
Electric Potential Energy
 What is Electric Potential Energy?
 Potential Energy – energy stored in an object.
 Kinetic Energy – energy of motion.
 Electric Potential Energy – electrons have stored energy
and the ability to do work after they leave the battery.
 Electrons will help convert electrical energy into another
type of energy (i.e. heat or light)
Electric Potential Energy and Voltage
 Electrochemical Cells – converts chemical energy
into electrical energy stored in charges.
 Battery – a combination of one or more
electrochemical cells.
Brainiac –
Electric Fence
Electric Potential Difference
 The Potential Difference is the change in the
amount of electric potential energy per one
coulomb of charge  called the voltage
 Unit of Voltage – Volts (V)
 Voltmeter – a device that measures the amount of
potential difference between two locations of
charge separation.
Potential Energy vs. Potential Difference
 Potential Energy
a) climbing stairs
b) climbing with a heavy pack on
(more work = more potential energy)
Potential Energy depends on both height moved and mass moved
 Potential Difference
In a battery, potential difference is like the height of the stairs
and the amount of charge separated is like the mass moved up
the stairs
So in a battery, potential energy is due to both the potential
difference (volts) and amount of charge separated (coulombs)
Classifications of Batteries
What are two different types of batteries?
Dry cells
Examples of devices that use dry batteries
(flashlights, portable CD players, MP3s, iPods, and watches)
Wet cells
Examples of devices that use wet batteries
(cars, motorcycles, electric motorcycles)
Classifying Batteries
Dry
Wet
Dry Cell Battery
Dry Cell Battery Parts
Positive Terminal
Carbon Rod
Electrolyte
Moist electrolytic paste
Plastic Insulator
Negative Terminal
Zinc metal
Common disposable battery
found in electronic devices
Simple Voltaic Wet Cell
Wet Cell Battery Parts
Positive Terminal
Lead (IV) oxide (PbO2)
Electrolyte
Sulphuric Acid (H2SO4)
Negative Terminal
Lead metal (Pb)
Common battery found in
automobiles, golf carts,
etc., can be recharged.
How Batteries Work
How do Batteries Work?
 Batteries have two terminals called electrodes
(made of two different types of metals)
 These electrodes are in an electrolyte
(a substance that conducts electricity)
 The electrolyte will pull electrons off one metal 
creating a positive charge on one electrode and a
negative charge on the other electrode
 This produces a potential difference (voltage) between
the two electrodes.