Which is the best wattage for an resistor?

I went to the electronics shop looking for a resistor, but they said for me choose the wattage! As far as I know, the wattage of a resitor is calculated by its current or voltage. Please help me!

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UziMonkey8 years ago
The wattage is the amount of energy the resistor can dissipate without failing. This depends on your application, but use Joule's Law of P = I * I * R. If your circuit operates at 50mA and the resistance is 330 Ohms, the power dissipated by the resistor is 0.825 Watts. Resistors come in 1/8th watt, 1/4 watt, etc values, so you'll need something that can dissipate at least 0.825 Watts without failing.

When in doubt, get a bigger wattage. It'll be physically larger, but have the same properties as the smaller wattage resistors.
FrankieS91 year ago

hi, i wonder if making a series of 1/4 watts would lower the overload of the resistors? meaning if the resistor are 1/4 watts max, so can i add more of resistors to increase watts max in a series ??? i got 1/4 resistors and i am trying not to burn the resistor out and i am using 12 volt and it produce 5 watts and the amps is .42!! Any ideas

talk2eric1 year ago

I'm trying to figure out what watt resistor to get for this hearing aid project. Does anybody know the wattage of a resistor with the description R-US_0204/2V? Thanks.

It really depends on your application. For most things that hobbyists will be doing the standard 1/4 W resistors will work just fine. As UziMonkey said, you can use P=I2*R or P=V*I to compute the power.
Hi there,

I am Mohanraj. S, working as Course Manager for a Robotics course which is purely designed in an easy  way to embed the Robotic technology in children minds.

This course is under construction which is especially for children studying from 4th std. to 9th std.

Am using Express PCB software for designing small PCB Boards for children.

My request - I need guidance from you sir, (some tips related to Robotics or Electronics)

If you are interested i will provide the information about this course

Regards,

Mohanraj. S
Sandisk1duo8 years ago
1/4
Hi there,

I am Mohanraj. S, working as Course Manager for a Robotics course which is purely designed in an easy  way to embed the Robotic technology in children minds.

This course is under construction which is especially for children studying from 4th std. to 9th std.

Am using Express PCB software for designing small PCB Boards for children.

My request - I need guidance from you sir, (some tips related to Robotics or Electronics)

If you are interested i will provide the information about this course

Regards,

Mohanraj. S
Higher wattage resistors are bigger, of course. You can almost tell the wattage by how big the resistor is. Also, just because a resistor is rated at a certain wattage doesn't mean it won't fail at that power level. All of those watts have to be dissipated into the environment. You don't have to worry about that though, as long as there's enough airflow. You're probably going to blow a few before you get used to it. Many components have died in the name of design. RIP.
Hi there,
I am Mohanraj. S, working as Course Manager for a Robotics course which is purely designed in an easy  way to embed the Robotic technology in children minds.
This course is under construction which is especially for children studying from 4th std. to 9th std.
Am using Express PCB software for designing small PCB Boards for children.
My request - I need guidance from you sir, (some tips related to Robotics or Electronics)
If you are interested i will provide the information about this course

Regards,
Mohanraj. S