Ohm's Law Question

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Lebult

Copper - Posts: 66

Joined: June 13, 2003

Location: Canada

Posted: September 07, 2003 at 9:42 PM / IP Logged

Hey,

I'm a little confused with the Ohm's Law stuff.

What formula would I use to find the Wattage of my Amp?

I know it pumps 1000 watts @ 4 ohms using 14.4volts, but I need to find out how many Watts it'll pump at 2 Ohms using 12 volts.

An answer wouls be great, but the formula itself woulds better. I'd like to try to figure it out myself : )

aggie altima

Silver - Posts: 298

Joined: July 25, 2002

Location: United States

Posted: September 08, 2003 at 2:18 AM / IP Logged

Anybody can correct me if I'm wrong, but I believe that you can't use ohm's law using the input voltage to find power (watts).

Using the fact that the amp pumps 1000 watts @ 4 ohms using 14.4 volts, if you plug the voltage and resistance into the equation power=(volts^2)/ohms, the number you get is nowhere near 1000 watts, it actually comes out to 51.84.

Just remember that what the amplifier is doing is taking in the voltage from the battery, and then "amplifying" that voltage to a higher voltage. To use Ohm's Law, you should use the voltage measured at the speaker wires, not at the power wire. Again using the specs you gave and the voltage equation, the measured voltage at the speaker wires should be about 63 volts.

I hope this helps you in any way.

xetmes

Silver - Posts: 586

Joined: May 18, 2003

Posted: September 08, 2003 at 5:40 AM / IP Logged

its not really like there is one formula to do what you want, amplifiers are all different, and do not have the exact same relationships. you could try to say that it would be less than 2000 watts because half the impedance will usually double the power, and the lower voltage would reduce that.

ohms law will not help that much because you are dealing will power.

there may be a formula out there (im not sure) it may be complicate though.

auex

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Posted: September 08, 2003 at 8:37 AM / IP Logged

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padawan

Copper - Posts: 215

Joined: June 11, 2002

Location: United States

Posted: September 08, 2003 at 9:37 AM / IP Logged

Power (watts) always equals the Current X the Voltage...

P=IV or P=VI.

DYohn

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Posted: September 11, 2003 at 9:57 AM / IP Logged

What kind of amp is it? Generally a good manufacturer will supply the ratings you seek...

xetmes

Silver - Posts: 586

Joined: May 18, 2003

Posted: September 11, 2003 at 10:56 AM / IP Logged

padawan wrote:

Power (watts) always equals the Current X the Voltage...

P=IV or P=VI.

In a traditional sence it does, but he is talking about the output of the amp to the speakers, amplifiers are not 100% efficient, and therefore a good amount of power is lost as heat depending on the efficiency it will be different.

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Ohm's Law Question

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