Thanks. This brings me closer. If my 9v battery (the standard one that f= its into electronic devices) could provide enough "energy" to run a car, co= uld I still plug it into my radio alarm clock without changing any of the c= ircuitry (given that it requires 9 volts)? I believe what I have heard is = yes, given perfect conditions. I assume that the standard 9v battery tongu= e test wouldn't be wise in that case. :-) This is helping me understand the role of resistors in a circuit. =20 Lindy -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of= Bob Ammerman Sent: Tuesday, October 22, 2013 6:40 PM To: 'Microcontroller discussion list - Public.' Subject: RE: [OT] Thought experiment: Understanding volts vs amps A simple way to understand this: The voltage rating of a power source describes its abiltity to push current= through a load (resistance).=20 Doubling the voltage doubles the current (assuming you don't change the loa= d). The current rating of a power source describes the _maximum_ amount of curr= ent the source can supply at the rated voltage. The _actual_ current supplied by the power source is determined by the resi= stance of the load and the voltage provided. I am sure you have heard of Ohm's law. It simply states: Current (in amps) =3D Voltage (in volts) / Resistance (in ohms) Notice that doubling the voltage doubles the current for a given resistance= .. Doubling the resistance halves the current for a given voltage. You can algebraically shuffle the terms in Ohm's law to solve for any of th= e three values, given the other two: Voltage =3D Current x Resistance Resistance =3D Voltage / Current To add a little more explanation:=20 The power being consumed by a load, measured in watts, is the product of th= e voltage and the _actual_ current through the load. The power that _can_ be supplied by a power source, is the product of the v= oltage and the _maximum_ current the source can supply. -- Bob Ammerman RAm Systems -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of= David C Brown Sent: Tuesday, October 22, 2013 11:06 AM To: Microcontroller discussion list - Public. Subject: Re: [OT] Thought experiment: Understanding volts vs amps The short answer to your question is :YES. BUT it would be a very large battery. The typical annual energy consumption for my home is about 9,000kWattHours = or 9 ,000,000WattHours At 9 volts that is 1,000,000AmpereHours A typical ca= r starter battery is 50 AmpereHours So your hypothetical battery would need= to be 20,000 times larger than the car battery Since a car battery occupie= s about 0.5 cu foot you are looking at a battery of 10,000 cu feet. or a 22 foot cube. Hope you have a big yard :-) Dave On 22 October 2013 13:21, Lindy Mayfield wrote: > I've spent years, on and off, trying to understand what volts means=20 > and what watts or amps or current means. Literally since I first=20 > opened a book about electronics when I was small. > > I may perhaps be close. > > Given matter to energy conversion rules and laws, and adhering to all=20 > known laws of physics... > > What if I had a 9 volt battery that could easily supply all the power=20 > necessary to my home for 1 year. Or power a small neighborhood for a=20 > day no matter what the energy consumption... > > This would be indeed an efficient chemical battery, but given the=20 > right technology, it could be done, no? > > Given that: Could I plug that same 9 volt battery into something=20 > small, like a TV remote control, or a hand-held radio? In place of a=20 > 9v battery that I can buy today? Without any changes to resistors,=20 > capacitors, transistors? No changes to the circuits? > > And further, could that same 9 volt battery be used anywhere a battery=20 > is required, a car starter, a toy, an electric wheel chair, an=20 > electric train normally powered by a diesel? Assuming that in some=20 > cases the voltage will need to be changed? > > It's probably painfully obvious those are my questions, not any out of=20 > a book or for a class. :) > > Thanks! > Lindy > > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive=20 > View/change your membership options at=20 > http://mailman.mit.edu/mailman/listinfo/piclist > -- __________________________________________ David C Brown 43 Bings Road Whaley Bridge High Peak Phone: 01663 733236 Derbyshire eMail: dcb.home@gmail.com SK23 7ND web: www.bings-knowle.co.uk/dcb -- http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/chang= e your membership options at http://mailman.mit.edu/mailman/listinfo/piclis= t -- http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/chang= e your membership options at http://mailman.mit.edu/mailman/listinfo/piclis= t --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .