mosfet - Is this a good circuit to control LED?

I'm taking an intro electronics course, and we recently covered MOSFETs. Would the circuit below work for controlling a 3W LED? Here is the part info. The LED wants about 1A of current. I'm thinking I can use the variable resistor to set \$V_{gs}\$ on the MOSFET so that it allows 1A to flow to the LED. For the 5V supply I have a computer power supply, so I could actually use other wires and get 3, or 12 V.

Answer

Yes you can make this work. As tcrosley points out, you'll end up with 1A @ 2.5V across your FET so you need to dissipate 2.5W or so (M1 will need a heatsink).

A more efficient circuit (less heatsinks) would be to use a buck converter and measure the led current with a sense resistor. Then use feedback to set the buck voltage according to the brightness you want.

If you are stuck with the 5V supply then another option is to use two of your leds in series. That way you get some more light.