light bulbs and batteries

[clintbryson]

What type of battery would I need to power a standard 40 or 60 watt light bulb?

 

[Johnson777717]

Well looking at Ohms law, Watts = Voltage x Current (W=EI)

If you have a 40 watt bulb, W = 40, then you could solve for the remaining values of E and I by assigning a voltage or current level that you wish to use.

For instance 40watts = 12 volts x I
With a 12 volt battery, you would need 3.333 amps of current. As you increase the voltage of the battery, less current is needed. So if we increase the voltage to 24 volts: 40watts = 24 volts x I, so the current necessary would be 1.667 amps.

You can solve for voltage in the same manner.

Also, please check the ratings for the light bulb that you are planning to use. As you may know, light bulbs can only handle so much current and voltage.

Please see the "Ohms Law" tutorial in this forum under Theory articles, for more information about Ohms law.

I hope that this helps.

 

[Painandsuffering]

ohms law

No offense to you older guys who still use E for Voltage but according to my instructor who has many years of Electronics background Voltage is symbolized now by V which makes it a lot less confusing for new people.

 

[Roff]

What type of battery would I need to power a standard 40 or 60 watt light bulb?

When you say "standard", do you mean the kind that you put in lamp sockets in your house? If so, you need around 110 volts, AC or DC to get them to standard brightness. Eight to ten car batteries in series will do the trick. An inverter might be easier.

 

[Johnson777717]

No offense to you older guys who still use E for Voltage but according to my instructor who has many years of Electronics background Voltage is symbolized now by V which makes it a lot less confusing for new people.

Well either way, as long as you know what is happening. I'm only 24 and I've been taught the "E" way. I suppose different areas of the world teach things a little differently. I agree with using "V" because it is easier to understand, it's just my well-aged instructors voice in the back of my head saying " E, not V".

 

[Nigel Goodwin]

Well either way, as long as you know what is happening. I'm only 24 and I've been taught the "E" way. I suppose different areas of the world teach things a little differently.

I'm 48 and was taught V, is E an American thing?, they still use the old symbol for resistors as well :lol:

 

[Roff]

Well either way, as long as you know what is happening. I'm only 24 and I've been taught the "E" way. I suppose different areas of the world teach things a little differently.

I'm 48 and was taught V, is E an American thing?, they still use the old symbol for resistors as well :lol:

Hey, my old resistors resist just as well as your new resistors.
Regarding E and V - I was taught both (I'm 63). I generally use V, but I really don't care.

 

[Nigel Goodwin]

Hey, my old resistors resist just as well as your new resistors.

Do they have stripes on them?, or are they 'body, spot, tip' (I wouldn't swear that's the right way round, they were before my time!).

 

[chaotic-mind]

I'm 48 and was taught V, is E an American thing?, they still use the old symbol for resistors as well :lol:

What symbol would that be?

 

[Nigel Goodwin]

I'm 48 and was taught V, is E an American thing?, they still use the old symbol for resistors as well :lol:

What symbol would that be?

The old symbol was a zig zag line, the new one is a rectangle. I think it changed in the early 1970's or so.

 

[Johnson777717]

I find the old symbol for resistors much more descriptive. The new rectangle is a little vague, unless values are given. Would it be technically correct to use the zig-zag on production drawings? My Electronics drafting book used the zig-zags, I think the book was published in the late 90's (I can't check because I gave the book to my buddy who's doing a little studying.) I think this would have to do with ANSI?

 

[magickaldan]

Actually all my books have the zigzag for the resistors and I prefer that over the box and I'm just 15. These books were published last year by radioshack.
The first test I took for electronics was in 7th grade, a couple of years ago, and was a state test, I got first place. Everyone always told me I was good at this stuff, and I guess that proved it to me.

 

[Nigel Goodwin]

Actually all my books have the zigzag for the resistors and I prefer that over the box and I'm just 15. These books were published last year by radioshack.

As I said, America is still using the old symbol for a resistor, not to mention the old Imperial measurements (or at least their version of them).

Having said that, I'll be asking for 'a pound of bacon' in the supermarket later on today :lol:

Although the UK is supposedly metric, and all items like that have to be sold in Kg - almost all shops give the price in both metric and imperial, in fact even more so than they used to a few years ago!.

 

[jamesmi]

I'm taking college classes now, and as far as E and V is concerned we use both in physics. We use V as the voltage drop across a particular device and E for the electromotive force of a battery. That's were the E comes from. So when we talk about the voltage of a capicator or the voltage drop across a resistor it's given as V, and when a battery is given it is usually stated to have an electromotive force of say 12Volts.

I'm also taking a engineering circuits class and we only use V. But we aren't really dealing with batteries that much. Usually it's voltage sources that may vary with time so we use V(t).

 

[Johnson777717]

Having said that, I'll be asking for 'a pound of bacon' in the supermarket later on today

Apologies for my misunderstanding: Do they really sell bacon by the pound over in the UK???

I am looking at my drawing template for electronic diagrams, made by Staedtler. The template states that it complies with ANSI Y32.2 1970 and IEEE No. 315 Mar 1871. The template uses the rectangle and the zig zag for a resistor! So according to ANSI and IEEE, the correct way is either or.

I'm assuming the rectangle resistor is used when actual scale drawings are made (where the actual space a resistor is to consume would be necessary), and the zig zag is used when concept drawings are made (when spacial considerations aren't too important)???

I'm taking college classes now, and as far as E and V is concerned we use both in physics. We use V as the voltage drop across a particular device and E for the electromotive force of a battery. That's were the E comes from. So when we talk about the voltage of a capicator or the voltage drop across a resistor it's given as V, and when a battery is given it is usually stated to have an electromotive force of say 12Volts.

The E with power supplies. and the V with point-voltage, kind of makes sense when you think about it.

I guess the world will leave it to us engineer/technical/hobbyist junkies to battle it out in order to find which is best. I suppose that there isn't a real "right" answer, but it is fun discussing.

 

[Nigel Goodwin]

Do they really sell bacon by the pound over in the UK???

Not 'really' - but they give the price for both kilograms and pounds, and if you ask for a 'pound of bacon' (as I did earlier on today) they sell you 0.45Kg instead :lol:

I don't see how the metric changeover can be complete until the pre-metric generations have died out. The weather forecasts here give temperatures in C and F - I don't have a clue how cold or warm temperatures in C are!. Same with measurements, I'm happy to work in either (or both), but if you asked me how long I wanted something I'd say "six inches", never "15 cm's".

I grew up using Pounds, Shillings and Pence - and I still tend to thing in that way, I still commonly call a 50p piece "ten bob".

 

[Painandsuffering]

V

Actually Johnson I'm in the U.S. Just like you and I've heard both v and e but like the other fellow in college said E is Electromotive force which is actually EMF but still I think its easier with v for voltage and e for electromotive so theres no mix up. and one more thing Johnson Ohms law is V=I*R not W=I*V because W=I*V is watts law not ohms law sorry man but I ahd to point it ou for the persons help!

 

[jimmything197]

E vs. V

Although I actually use V most of the time, if not for E, we would never have ELI the ICE man!!!!

I don't know if you guys use that, but my reaaaaaaaal old circuits 1 teacher used it to tell us that in an inductor, current follows voltage, and in a capacitor, it's the other way around. Not much sense in VLI the VCE man...

Also, I vote that resistors remain zig-zags forever, because once you start making them rectangles, schematics start looking like flow charts and my fun is lost. Just my personal opinions....

 

[Nigel Goodwin]

Re: E vs. V

Also, I vote that resistors remain zig-zags forever, because once you start making them rectangles, schematics start looking like flow charts and my fun is lost. Just my personal opinions....

It's a bit late to vote :lol: they changed over 30 years ago :!:

 

[Johnson777717]

Actually Johnson I'm in the U.S. Just like you and I've heard both v and e but like the other fellow in college said E is Electromotive force which is actually EMF but still I think its easier with v for voltage and e for electromotive so theres no mix up. and one more thing Johnson Ohms law is V=I*R not W=I*V because W=I*V is watts law not ohms law sorry man but I ahd to point it ou for the persons help!

Thank you Pain, i appreciate the clarification.

I did some pondering on the whole E vs V topic. It seems to me that E is the basic system of measurement, while V is the unit of measure for E. It is in comparison with Weight being the basic system of measurement, and pounds (grams, grains etc.) being the actual unit of measure. Again, the same concept arises with distance being the system, and inches (meters etc.) being the actual unit of measure.

Does that make sense? So if you're speaking in terms of theory, "E" would technically be the proper term, and if your speaking in terms of an actual application or concept involving units of measure, "V" would be the proper term. Agree?