What does the rating on speaker mean?

[scream_er]

I have a speaker which has 8ohms and 0.5W written at the back. What does that mean? From this can I calculate the max or min voltage or current the speaker can take?

 

[jeet_asic]

You have power = 0.5 W and resistance = 8 ohms , so by P=( I^2) . R , you get I = 0.25 ampere and V=2 Volts. It means that your speaker has power capacity of 0.5 watts with 8 ohm resistance load.

 

[alexan_e]

Also note that a typical 8 ohm speaker doesn't have a constant 8 ohm impedance.
See how a typical speaker impedance vs frequency looks like

see how a 8 ohm (blue) and 4 ohm (red) impedance graph looks like



Home Toys Article - Speaker Impedance, Your Amplifier And You.

 

[Ogu Reginald]

It means that the impedance of the speaker is 8ohm while the power rating is 0.5watts.

---------- Post added at 14:13 ---------- Previous post was at 13:48 ----------

It means that the impedance is 8ohms and the power is 0.5watts. You can calculate the voltage and current using the normal ohm's law.

 

[scream_er]

So anyway, I want to know what rating of speaker I need to connect to an amplification circuit that can output 5V maximum. More specifically 0V to 5V. The voltage of a 0.5W and 8ohm speaker is 2V, so i guess that means the speaker will be blown if I use it?

 

[Syncopator]

I want to know what rating of speaker I need to connect to an amplification circuit that can output 5V maximum.

That depends on whether 5V is peak to peak, peak or r.m.s.

If peak to peak, i.e. 1.77Vrms, that's 0.4W in 8 ohms, so your 0.5W 'speaker would be suitable.

If it's pk, i.e. 3.535Vr.m.s., that's 1.56W in 8 ohms.

And, if it's r.m.s., that's a bit over 3W in 8 ohms.