# basic electronics questions

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#### tooandrew

##### New Member
Resistors, i know how to calculate ohms needed but i assume its important to know the watt rating how does that work?

second question, how would one wire a tri color led? i know there are three leads, so... i'm not entirely sure.

capacitors- if i wire them in parallel, will they all charge at equal rates, and charge completely?

also im new here so hi everybody. first post

#### Diver300

##### Well-Known Member
Resistors, i know how to calculate ohms needed but i assume its important to know the watt rating how does that work?

The power rating of a resistor, measured in Watts, is how much heat it can get rid of. Resistors convert electrical power into heat, at the rate of VI (the voltage times the current) or V²/R or I²R, they are all the same. That heat has to be got rid of or the resistor will overheat. The physically larger the resistor, the larger its power rating.

second question, how would one wire a tri color led? i know there are three leads, so... i'm not entirely sure.
Usually they are just two LEDs, a red and a green one. When both are lit it looks yellow. The cathodes (negative connections) of both LEDs share one wire. The other wires are the anodes (positive connections) and they are separate so that the LEDs can be powered separately.

capacitors- if i wire them in parallel, will they all charge at equal rates, and charge completely?

Yes, they will charge equally, as there will always be the same voltage on both capacitors, and the voltage is directly proportional to the charge.

However, you don't usually charge capacitors "completely". They are not like batteries where "fully charged" is a useful concept. Capacitors have a maximum voltage rating, which should never be exceeded, but it is common to over specify that by quite a lot. For example, if you want a capacitor on a 5 V supply, you can buy them at 6.3 V or 10 V ratings. It would be normal to use the 10 V ones at 5 V, to improve reliability.

I hope this helps.

#### Grossel

##### Well-Known Member
Resistors, i know how to calculate ohms needed but i assume its important to know the watt rating how does that work?
Lot more tricky. Depends of the ambient temperature and air flow.

second question, how would one wire a tri color led? i know there are three leads, so... i'm not entirely sure.
Often, the center tap is to find in middle. To be sure - do a diode test on it. Most multimeters have diode test function.

capacitors- if i wire them in parallel, will they all charge at equal rates, and charge completely?
The voltage over each of them would be equal. What do you mean with equal rate?

also im new here so hi everybody. first post
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