Higher resitance, lower power consumption?

Using the 2 formula's:
U = IR
P = U
I

If the voltage is constant and the resistance increases, the current decreases.
for example:

3V, 10ohms = 0,3A
3V, 20ohms = 0,15A

if the current decreases the power decreases
3V; 0,3A = 0,9W
3V; 0,15A = 0,45W

The power consumption in 1 hour is than
0,0009 KWh
0,00045 KWh
Does that mean that the higher resistance the lower the power consumption?
That doesn't make sense to me because, if you have 2 speakers instead of 1 speaker,
wouldn't the power consumption than decreases?

Floris

florisfassin:
Does that mean that the higher resistance the lower the power consumption?
That doesn't make sense to me because, if you have 2 speakers instead of 1 speaker,
wouldn't the power consumption than decreases?

If the speakers are connected in series, the total resistance is higher, so total current and therefore power consumption is lower.
If the speakers are connected in parallel, the total resistance is lower, so total current and therefore power consumption is higher.

Thanks!

florisfassin:
The power consumption in 1 hour is than

That's energy, not power.

Speakers are a lot more complicated not being a pure resistance. See Link

Russell.

, if you have 2 speakers instead of 1 speaker,
wouldn't the power consumption than decreases?

With speakers, you can just turn-down to volume if you want less power... :wink:

Two speakers in series (with the same voltage) is half the power (compared to one speaker) and half the loudness -(3dB). A speaker converts electrical energy into sound (and heat) and adding another speaker doesn't make the conversion any more energy efficient.

Two speakers in parallel are twice the power and twice the loudness (+3dB) compared to one speaker.

People sometimes use two speakers (or lower impedance speakers) to get more power out of an amplifier. But, the amplifier has to be rated for the impedance load. For example, most home stereos will overheat with less than 4 Ohms, but some high-power car stereo amps can go down to 1 or 2 Ohms.

Note that although a 3dB change is a power factor of two, it doesn't sound half as loud or twice as loud. A 3dB change sounds like a small loudness change, because our ears are not linear.