Resistance vs. Power?

[bill_fimm]

Hello All.

I have been digging around for the last few days, but couldn't find any info on this.. This is probably a no-brainer for experienced builders, but I don't completely have and understanding of this yet.

One of the die on my tri-cree calls for a 1 ohm 2W resistor. I want to do a little cheap-o custom color mixing, so I tried it with a 4.7 ohm, to back that particular die off a little. I like the results.. So my question is: If I am using a resistance value higher than what is calculated for that die, do I have to use a larger wattage, or will 2 Watts be ok? Does increasing the resistance mean the resistor will need to dissipate more heat?

I have seen TCSS youtube video about using resistors to color mix, but it didn't mention anything about increasing wattage, just recommended a 3 or 5 watt. I really would LOVE to use the smallest possible, the 5W is huge, and I know i'll have difficulty fitting it in my hilt. Thanks again.

[FenixFire]

You need to calculate the wattage as well.

Wattage calculation
The Ohm's Law gives us P = U . I with again U being the voltage across the resistor and I the current in the circuit, and we now know both of them.
P = (Vsupply – Vled) * LedCurrent

[bill_fimm]

Ok. (Vsupply-Vled) * LedCurrent
So thats (4v - 3.15v) * 1 Amp
Which is (.85v) * 1 Amp = .85 watt

Is that correct? A 2 watt resistor will be more than enough then, correct??

The value of the resistor does not matter when calculating the wattage?