Again only three problems, on account of Thanksgiving:

1. Text, Chapter 7, problem 4

2. Text, Chapter 7, problem 10

3. Suppose we want to feed 9 W of power into a loudspeaker. The loudspeaker "impedance" (treat it the same as resistance) is 4W.*

1. What is the current we must feed into the speaker?
2. How much voltage must the amplifier put out to drive that current? What common device provides a voltage of about that size (that is, is it like the voltage used in a flashlight, or more like that used by a toaster, or ...)? Not that there is much of a point in connecting such a voltage source to a loudspeaker, you are just supposed to get a "feeling" for the sort of voltages put out by a power amplifier.
3. Now we connect two speakers in series to an amplifier with the same output voltage as what you found in (b). This output voltage is now divided evenly among the tow speakers.
4. So what is the power fed into each speaker? Into the two together? Which arrangement will sound louder, the single speaker, or the series combination?
5. How loud is the speaker output, for the 9W input? Assume the speaker is 1% efficient (1% of input electrical energy becomes acoustical output -- not an unreasonable number for speakers) and assume the power is spread over 1 mē at the listener. What is then the intensity (in W/mē) and the SIL (consult table on p. 151)? Is that quite loud or whisper quiet?

*If your browser is Nescape 7 it may not recognize the W as a Greek Omega, the symbol for "Ohms". Earlier versions of Netscape should have not problems with this :)