i didnt say vs-vl=i/r i said vs-vl= i X r v=ir is the way i have always done it i thought thats the way it was ment to go ... its the way wikipedia has it http://en.wikipedia.org/wiki/Ohm's_law
its actually (delta)V=ir which is (V sub I) - (V sub F)=(I)x(R) if and only if (V sub I) is greater than (V sub F) difference in voltage is equal to Resitance mulitplied by current where Initial Voltage is > FInal Voltage. I learned subs for stuff I think this is right nexxo want to make sure. basically you need to know basic math and about simple electronic formulas and you can use LED's if and only if you have a higher starting voltage than the LED is rated for.
by now i recon we have confused this guy to hell. and now i have run out of knowledge ... whats a sub?
errr..... Think I am understanding this... Just popped in for some advice, now have a pad of paper covered in scrawled calculations If you increase the resistance, that drops the amount of power that gets to the led right? And if so, does that make the led dimmer? How many (?) mcd should a normal (not super bright) case have? Keep seeing 10,000 as ultra bright and such which I don't want. Also, if the resistor does decrease the brightness of the led, can have a switch that add/removes a resistor? So sort of a brights/dims switch? I failed high school electricity so the less jargon the better. I can always learn the jargon and apply it to my laymans knowledge. Harder the other way Btw: Is this too off topic?
i think this thread has gone off topic allreddy. yes you could add a switch with a resistor in parallel, when the extra resistor was "switched" on the the led would get brighter.
if you add a resistor in parallel then the resistance will go down if it is added in series then the resistance will go up. http://physics.bu.edu/py106/notes/Circuits.html
@ linky That does clear things up (although I'm not too sure why that happens, I now know that it does ) So I assume it will be easier to add a resistor in parallel with a switch, just open that route (I don't know the terminology... ) to the current? Will read through more of those course notes (free education!) but am a little slow when it come to electricity (seriously, I just don't get it...) so any and all help is awesome So thanks a lot! Really appreciate it
Picture worth a thousand words jobbie Code: +5V----R1---+--R2--+----LED----0V | | +-o/ o-+ Switch The switch shorts out the second resistor so with the switch closed the LED gets more current, glows brighter. 60,000mCd may sound a lot, but compared to the light from a CCFL it's nothing much. It's also a very narrow beam, so try it before doing too much work fixing it in the case. bender's from Oz, they do things upside down.
If the switch is closed won't that force the current through the 2nd resistor? If I'm wrong its coz I can't read the pictures In my mind its all canals and locks So what i see is if the switch is open the water *cough* electricity will be diverted through the switch. So it will look (or act rather) like this: Code: +5V----R1---+ +----LED----0V | | +-o/ o-+ Switch and with the switched closed: Code: +5V----R1---+--R2--+----LED----0V No? p.s. sorry its taking me so long to twig
how does that switch effect anything? apart from giving another route for the +5v to go when on... as the R2 is still connected with the switch on or off
Electricity is lazy, it will always take the easyest route. In the above example when the switch is open the electricity is forced to go though the second resistor. With the switch closed the the electriciy bypases the second resistor and takes the easest route. Think of electricity as the moron in the sports car racing to get to work. Grrrrrrrrr i've lost the ability to type (dang typo virus)
Trust me... that's no huge statement where I'm concerned! So it will ignore the resistor completely... Mmm... that little trick will come in handy!
OH! I think I get it! By open do you mean not joined? Like when a bridge is up? I've been thinking open like a door.... So open would NOT allow the current to pass through, and closed would? I hope I'm right...
COOL! Although thats a pretty silly way of putting it glad I was not understanding because of something really incongrous, otherwise I'd just feel stoopid
Ok you might get this say you have a line from a pump. You have 2 water blocks you have a valve that will allow water to bypass the second block and not go through it since the block is terribly restrictive so you open the valve the water goes through the valve instead of the block since its easier now the stupid water will go through the block, which if the analogy used with people would be about 95% epople would go through the crouded exit and 5% would go to the other exit. hhehe. But sub is just something I wrote because I can't do subscript its just a way to give a variable a different identity or value as something with the same notation. So for volts you have starting and ending or in this case deisred. Now you can figure out how much current will pass through the resistor by multiplying the voltage drop from in to out of the resistor and deviding the wattage that the resistor can remove from the line that will be a minimum the more wattage the less the current will be restricted. You could get a rotary switch and have each setting change the resistance by a certain amount.
We've got [ sub]f[ /sub] tags that (without the space) give Vf Also [ sup]2[ /sup] superscript ones for x2 etc.
Yeah, I undestand it now. Only thing that was confusing me was that whenever someone said "open" I thought "closed"... I have my reasons....
