Re: Electronics 101 Question .....

Posted by MarkB_MI on October 25, 2006 at 18:14:52 from (64.31.11.12):

In Reply to: Electronics 101 Question ..... posted by MMB on October 25, 2006 at 15:35:07:

Whether you intended to or not, you gave us a trick question.

"...we have a circuit with 6 DC volts and 4 amps going into the resistor..."

So which is it? 6 volts or 4 amps?

If you are applying a constant voltage to the resistor, then the smaller resistance will draw more power. (P = V²/R) (So the 3 ohm resistor draws 12 watts, while the 10 ohm resistor draws 3.6 watts)

If you are applying a constant current to the resistor, the then the larger resistor will draw more power. (P = I² x R) (In this case the 3 ohm resistor draws 48 watts while the 10 ohm resistor draws 160 watts. Note that in the real world, you won't be able to get your 4 amps because you only have 6 volts to work with. You need either more voltage or a smaller resistor to get 4 amps.)

And if you are really trying to get 4 amps at 6 volts, then you need to solve for the resistance:
R = V / I = 6/4 = 1.5 ohms. And the power consumed by the resistor is going to be V x I = 24 watts. And a 24 watt resistor is physically pretty big, maybe the size of your thumb.

You might want to back up and say what it is you're trying to do. It's always better to work with a real problem rather than a hypothetical one.

Replies:

Add a Reply Name: E-Mail: Subject: Comments: Optional Link URL: Link Title: Optional Image URL: Email Notification: If you check this box, email will be sent to you whenever someone replies to this message. Your email address must be entered above to receive notification. This notification will be cancelled automatically after 2 weeks.

TRACTOR PARTS	TRACTOR MANUALS

We sell tractor parts!  We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]