130 likes | 221 Views
Notes on BATTERIES. What does a battery do?. Energy transformation: Chemical energy – stored in chemical compounds Electrical energy – moving charged particles (e-). Galvani. Luigi Galvani – Italian physician studied frog anatomy
E N D
What does a battery do? • Energy transformation: • Chemical energy – stored in chemical compounds Electrical energy – moving charged particles (e-)
Galvani • Luigi Galvani – Italian physician studied frog anatomy • Brass hook held frog leg in place & other end touched an iron railing. The leg twitched. • Believed the twitching of leg muscle due to “animal electricity” in living tissue. • Not true • He simply demonstrated the electrical basis of nerve impulse
Volta • Alessandro Volta reproduced Galvani ‘s results • Said that leg movement was not due to animal electricity but due to a chemical reaction between the two metals (brass and iron railing) & salty fluid in frog’s leg muscle http://www.sciencebuddies.org
1. Volta’s Battery FIRST BATTERY • Layered salt-water-soaked paper layered between zinc & silver • Connected wires & produced current • More layers – more current
2. Electrochemical Cell • Device that transforms chemical energy into electrical energy Components • Electrodes – 2 different metals • Electrolyte – substance that conducts electricity (salt water or acid) • Terminal - part of electrode above electrolyte, used to connect to circuit
3. Creating a Voltage • Voltage is created through a chemical reaction • Electrolyte reacts with each electrode • One electrode loses electrons & becomes (+) • Other gains electrons & becomes (-) • Electrochemical Cell Information from Mr. Kent's Chemistry Page http://www.kentchemistry.com
3. Creating a Voltage • The electrons leave the zinc (becomes positive) and go to the copper (becomes negative) • Explanation of Voltaic Cells from HyperPhysics http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/electrochem.html#c2
3. Creating a Voltage FYI http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/electrochem.html#c2 http://en.wikipedia.org
3. Creating a Voltage • The opposite charges is the difference in electrical potential energy or voltage • Causes electrons to move from through the circuit = current http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/electrochem.html#c2
Video http://www.youtube.com/watch?feature=player_embedded&v=A0VUsoeT9aM&safety_mode=true&persist_safety_mode=1&safe=active
4 and 5. Batteries • BATTERY = several stacked electrochemical cells • Total voltage = all the individual cell voltages added together • Wet Cells – electrolyte Dry Cells – electrolyte is liquid – salt water is a paste (KOH or NaOH) or acid (car battery) (AAA, AA, C, D - alkaline)
6. Terminals with Same Charge • There will be no current if the terminals had the same charge because there would be no voltage between the terminals. With no voltage there is no current.