Hw

By next class, I will assign a large homework assignment, akin to a take home test. It wil be due two classes later. It will be due in class.

Prepare for this. You may only use your notes - no online resources, books or outside help.

There will be 3-4 questions focusing on all things electrical:

Electrostatics
Circuits
Magnetism
electromagnetic induction

HW, E - sorry for delay

1. What is magnetic flux?

2. What is the unit of magnetic field strength?

3. What voltage is induced in a coil of wire (100 turns) if a magnetic field goes from 0.1 T to 15 T in 2 seconds? The coil has a radius of 0.1-m.

4. Now imagine that the coil above has a 15 T magnetic field hitting it constantly, but the coil rotates around it once every 0.5 seconds. What is the maximum voltage tha will be induced?

5. What is Lenz's law and how does it apply to the falling magnet demo?

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.