E homework

From today's class, research the following:

Faraday's law
Electromagnetic induction

If you have time, read about speakers and microphones.

homework

C block:

Explain the basic operation of a (DC) motor.
Also, explain the operation of a speaker.

quiz, lab, etc.

Quiz (Weds) for E block; Thursday for C block.

Study series and parallel circuits. There *may* be a bonus question on combination circuits.

Also, ready your lab report. Drafts due this week. Final lab due Tuesday (E) and Wednesday (C).

Practice combination circuit below - a couple tricky ones! Find the total resistance in each circuit, the battery current and all voltages and currents.

Lab Questions for Ohm's Law lab

So far, you've done 2 graphs: I vs. R, V vs. R. They will be included in your lab. Don't forget titles, units, etc.

Lab questions

1. Examine the 2 graphs. Do they make sense? Why? What's going on in them? Do they appear to obey any mathematical relationship/equation?

2. You've determined experimental resistances for each trial. Are they within 10% of the expected/theoretical values? Should they be? If not, why are they not so good?

3. What does it mean exactly if something follows Ohm's Law? Do all electrical devices follow this law? Are there substances that definitely are not "ohm-ic"?

4. Other than the batteries "dying," what might happen as the batteries are connected to the resistors? Would the V and I values change?

5. What is meant by "internal resistance" of the battery, and how does it affect this experiment (your results)?

6. Give ways to improve this experiment.

7. Discuss the basic way to use the meter to measure current and resistance. (I ask you this to make you think about it; on an upcoming test, you'll be required to do this.)

8. Anything else you want to conclude or talk about.

9. Hooray!

HW (E)

Try this combination circuit problem:

Find:

a. total resistance

b. battery current

c. current through each resistor

d. voltage over each resistor

Lab questions coming shortly.