I’ve only taken a few physics classes all my life. I learned about amps and watts and how to measure them but there’s something bugging me, I don’t know what characteristics of a battery determine its voltage. I remember checking out a book on electronic experiments back in elementary school and reading a section about volts. It said if you took two different little metal strips and dipped them in a salt solution you’d get about a volt and a half. Then it asked the reader what would happen if you did the same thing with mile long strips of the same metals at the bottom of a salty ocean, it said you’d still get about a volt and a half.
What determines a battery’s voltage? I guess its not the size. Is it the different metals being used?, as in their capacities for electrons?
The electrochemical properties of dissimilar materials determines the voltage of batteries. For example an ordinary dry cell has a carbon rod as one electrode and a zinc case as the other with an electrolytic paste in between them. The open circuit voltage of this combination is 1.5 volts. Other combinations of material will have other voltages.
Typical open circuit voltages of various battery chemistries:
NiCd: 1.20 V NiMH: 1.25 V Carbon-zinc: 1.50 V Silver oxide: 1.55 V Alkaline: 1.58 V Zinc chloride: 1.60 V Lead-acid[: 2.0 V Lithium: 3.0 V Lithium thionyl chloride: 3.67 V
In Physics: When a battery is connected in a circuit, this creates a potential difference (V). This potential difference is the difference in potential energy of the charges that are in the conductors at the terminals of the cell/battery.
In Chemistry: The common dry cell is made of a zinc anode, graphite cathode, and electrolyte paste of MnO[sub]2[/sub] ZnCl[sub]2[/sub] and NH[sub]4[/sub]Cl. This has a maximum EMF of 1.48 V. This value can be obtained by the oxidation and reduction potentials of the reactions involved. Other cells using other reactions give different E values.
Perhaps one of the above can be attributed to the voltage of a battery.
Also, a battery refers to a group of cells connected in series. So batteries, as we know them, shouldn’t really be called batteries.
Sorry if the above information is not pertinent or correct, as they are from my (sometimes poor) memory.
Oh, and I guess I’m new here. Hello everyone at SDMB.
The EMF is the voltage of the cell. The voltage of the battery is determined by the type of cell, and the number of cells. If you have 6 of your 1.48 V (1.5 V, close enough) cells in series, you end up with a 9 V battery.
No wonder I can’t get my blender to work.
But seriously, once again it is made clear that I should avoid topics, like this one, that are beyond me. I spouted off without thinking (as usual) in a topic about which I am not qualified to answer. I hope you will all forgive me.
