ohms law (1 Viewer)

[betterthenatent]

Can anyone refresh my memory on ohms law. We are having our first trip of the year next week and I thought I might take a 1-2 w fan heater will this be OK on a hook up. A few examples would help.

 

[Munchie]

OHMS law states that the current flowing in any conductor is directly proportional to the EMF and inversley proportional to the resistance providing the temperature remains constant.

If my memory hasn't failed me.

 

[peter H]

Power (watts) = Volts X Amps

or

Amps = Watts / Volts

so

2000 watts / 240 volts = 8 amps approx

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[callumwa]

P = I x V

Power (P) in watts = (I) current in Amps x (V) Voltage in Volts

1 Kw rated heater is 1000 watts, so at 240 volts is drawing approx 4amps....

2Kw (2000 watts) drawing approx 8 amps... and so on..

 

[betterthenatent]

Thanks for the replies. I sort of had an idea that was it but some how I thought a 1kw appliance would draw more currant.

 

[rainbow chasers]

ohms law = oh my god, the whole site has gone out!

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[lunarman]

Not wishing to be pedantic but ohms law makes does no reference to power.

Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference or voltage across the two points, and inversely proportional to the resistance between them.

The mathematical equation that describes this relationship is: I = V/R

where I is the current through the conductor in units of amperes, V is the potential difference measured across the conductor in units of volts, and R is the resistance of the conductor in units of ohms. More specifically, Ohm's law states that the R in this relation is constant, independent of the current.

 

[Simannjo]

Ohms law = have on what you want untill the post trips...

 

[bigfoot]

Ohm sweet ohm

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[Gromett]

Draw a triangle on a piece of paper. Put the letter V at the top.
Put an I at the bottom left and an R at the bottom right.

Cover the one you want to find out with your finger and what is left is the formula.

For example you want to know what V is. The answer is IR
You want to know what I is. The answer V over R (V/R)

Power is Current X Voltage. Using ohms law and transposition of the above formulas you can work out.

W = I2R (I Squared x R)
W = IV
W = V2/R (V Squared over R)

There are 12 formulae in total using these 4 variables.

Bear in mind though that these only apply to resistive loads only. When you get into capacitive and Inductive loads you have to take Xc and Xl into account. These are Inductive Reactance and Capacitive Reactance but don't worry too much about these if doing rough and ready calcs for cabling etc.

However when working on 12V car gear, remember that the voltage can be as high as 14.4V when working out current flow in cables.

Karl

 

[Gromett]

Can anyone refresh my memory on ohms law. We are having our first trip of the year next week and I thought I might take a 1-2 w fan heater will this be OK on a hook up. A few examples would help.

Sorry my previous answer didn't answer your question.
W = IV.
Tranposed
I = W/V

Quick a rough way I use is each 1KW is 4 Amps. Not totally accurate but close enough for checking if a breaker will cope with a 1KW heater etc.

Karl

 

[dave newell]

You're not going to get much heat out of a 1-2 watt heaterr though.

D.

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[MicknPat]

I find this site great http://www.sengpielaudio.com/calculator-ohm.htm worth putting in your Bookmarks :thumb:

Mick

 

[DBSilverfox]

When I was at school they taught us to remember it as the girl's name - Ivy Watts. (I x V = Watts), and use the triangle trick.

Always stuck.

David

 

[golly]

Don,t forget when calculating your total Amps to take account of the battery charger and fridge etc. I have a card with the amps used by each appliance I use, then I know if I have to switch anything off before putting say the kettle on. Sad I know but better than tripping the post or even the site supply.

John

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[scotjimland]

Now that's been done... :thumb:

could someone explain E=mc2 (in laymen's terms)

Karl ?

 

[Geo]

Not sure on the fine details, but it has to do wit Museums:thumb:
Ohm is where the art is:Cool:

 

[Wildman]

Now that's been done... :thumb:

could someone explain E=mc2 (in laymen's terms)

Karl ?

there you go.

where E is energy, m is mass, and c is the speed of light in a vacuum. The formula is dimensionally consistent and does not depend on any specific system of measurement units. For example, in many systems of natural units, the speed (scalar) of light is set equal to 1 ('distance'/'time'), and the formula becomes the identity E = m'('distance'2/'time'2)'; hence the term "mass–energy equivalence

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[Terry]

Ohms law = have on what you want untill the post trips...

That sounds a good idea to me :thumb:Plug it in -if it works its OK
terry

 

[scotjimland]

Ohms law = have on what you want untill the post trips...

that's not Ohms law... that's Murphy's law oh:

 

[Simannjo]

that's not Ohms law... that's Murphy's law oh:

Aah... the universal constant...

If you need it - you wont be able to find it...
If you have 2 - You dont need any...
If you have a square one - You'll need a round one...
If you thought it was cheap - Someone will find it cheaper...

Etc... etc...

oh:

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[bigfoot]

The theory of relativity is that you don't see them for ages until the will is being read!!

 

[slobadoberbob]

I have read the posts and I am totally lost

Ok I give up, I am totally lost.. I will settle for the appox.. 1kw is 4 amps

I have been looking everywhere for a small 500watt heater... So far I use the 120 watt tube heaters.. On in the bathroom and one under the drop down table in the lounge area of the RV and they work well...if I need more heat I turn on the big heater supplied in the RV...

But as I say, having read the post cover to cover..it has me lost.

Bob

 

[Jaws]

A simple way to remember it is to think of the AVO emblem on the front of the Mk8's

So.. draw that on a bit of paper
Now, if you want to find resistance, ( Ohms )just draw a line and cut the O off
What you are left with is how to work it out ( so that would be V ( Volts, over A ( Amps

To find Amps, draw a line to cut the A off and again you are left with how to find the answer ( V/O )

Same goes for Volts.. to find volts simply times A and O

This is how I used to teach it many moons ago.. Simples
Here is an executive guide

Link Removed

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[coolasluck]

OHMS law states that the current flowing in any conductor is directly proportional to the EMF and inversley proportional to the resistance providing the temperature remains constant.

If my memory hasn't failed me.

OHMS Law
The force through a metalic object kept at a fixed temperature is directly proportionate to the potential differance.

 

[scotjimland]

there you go.

where E is energy, m is mass, and c is the speed of light in a vacuum. The formula is dimensionally consistent and does not depend on any specific system of measurement units. For example, in many systems of natural units, the speed (scalar) of light is set equal to 1 ('distance'/'time'), and the formula becomes the identity E = m'('distance'2/'time'2)'; hence the term "mass–energy equivalence

Nice try Roger ..

here is the correct theorem of relativetitty

Albert Einstein married his cousin.

He had tried to date outside his family
circle, but he never found any women appealing - especially in the boob
department - that weren't within his familial group.

He postulated that there is a special attraction to women in one's own family in his Theory of
Relative Titty.