Practice Problems

26.51, 26.89, 26.85, 26.101, 26.95, 26.97, 26.61

Practice Problems

I hope you all are doing your practice problems. Could someone post which ones I said to do please. If anyone is stuck I highly suggest that you discuss them here.

For Tonight

I have just finished posting all of the answers to the sample exam. I am going to keep the blog open for the rest of the night so feel free to comment and I will respond pretty quickly

25.8

1.19E7 m/s away from the Earth

24.6

39.2 degrees and assuming the omega is moving CCW ImaxZ should be behind ImaxR

24.5

L = 0.608 mH

R = 6.52 k(Ohms)

24.4

a) Z = 606 Ohms

b) increase (if you get something different THAT'S OK!!! tell me why you reasoned that way)

23.5

a) L = 4.22 H

b) 0.28 s

c) 1.64 A

25.6

49 degrees

25.7

3.85*10^26 W

25.5

a) 8.238*10^14 Hz

b) 8.203*10^14 Hz

24.3

a) 0.173 V

b) 7.84 V

c) 1.84 V

23.7

b) clockwise

c) (mgR)/(L^2)(B^2)

23.6

4.0 mWb

22.4

At A - 7.8 micro T (out of the page)

At B - 0

At C - 7.8 micro T (into the page)

22.3

arctan[(ILB)/(mg)]

22.2

up and to the left

All Conceptual Problems

post your answers and I will correct them

I Lied

Ok I just got home so I am going to post the answers to the sample exam as they become available

sinusoidal & square waves

what is the relationship between sinusoidal and square waves? just curious..

Sample Exam Answers

Sorry guys I have been out of town since Thursday morning and this is the first chance I have had to get onto the blog. I will be getting back at around 3pm tomorrow so I will try and post the answers ASAP and answer all of your questions that you posted around that time.

As#9: Polarization of Light and Malus's Law (PART F)

The question reads:

Notice that a polarizer modifies the light intensity according to Malus's law and also reorients the polarization angle of the beam to match its own transmission axis. Hence it is possible for light to pass through a pair of crossed polarizers if a third polarizer is inserted between them with an intermediate transmission axis direction. What is the new intensity of the light emerging from the final polarizer in Part E if a third polarizer (Polarizer A in the figure (Part F figure) ), whose transmission axis is offset 45 from each of the others, is inserted between the original two polarizers?

I thought that becuase the first polarizer and the third polarizer are perpendicular to each other, they would form an intensity of zero regardless of whatever angle the second polarizer is positioned at in the misddle. I dont understand this.

Any help?

25.46 Mastering Physics part B,C vs 25.44

to find the intensity, I used:
I1= c (8.85*10^-12) E^2 ---> part B
I2= c * B^2 /(4pi*10^-7) ---> part C

and finally got it right

but in the problem 25.44,
the Imax is given and Emax is asked
when I used the formula above I got it wrong, turned out needed to multiply by sqrt2 to get max value.

which formula is correct?

thanks

RLC lab (part 2: the capacitor)

when we're measuring the voltage of generator and the voltage across the resistor, why dont the waves line up?


Thanks

RL and RC circuit

why:

when an inductor and a resistor are connected in series, the voltage across the resistor after certain amount of time is V0 (1-e^t/time constant)

when a capacitor and a resistor are connected in series, the voltage across the resistor after certain amount of time is V0 (e^t/time constant)

He went over these in class but I forget

Please help
Thanks

Sorry it's out of topic

Sorry out of topic. But did anyone take my RLC lab by accident?
I really need that

thanks

To Study for the Exam

Doing problems that are harder than what is on the exam can STILL help you! Even if you get totally lost and confused half way through the problem this is IN FACT better than doing 20 easy problems you already knew how to do to begin with! Make sure you know:

1) How particles behave in the prescience(sp?) of a magnetic field (how does that differ if the charge is positive or negative)?

2) What kind of magnetic fields are produced from different sources (i.e. a current carrying wire, a moving charge, ect.)

3. How to do simple polarization problems

4. RC, RL, RLC circuit problems

5. AC circuit problems, WITH PHASORS!!!

6. Motional EMF (the thingy with the moving rectangle of wire into a magnetic field)

7. Calculating the magnitude and DIRECTION of the magnetic field from any source

8. the relationship (both VECTOR and otherwise) between the E and B-fields in a EM-wave

Mmmmmm.....how did I come up with this list?.......(that is a rhetorical question, please do not answer)

Question 25.44 Mastering Physics

The question asks:

What is the maximum value of the electric field in an electromagnetic wave whose maximum intensity is 5.50 ?
I know that I=C*e_o*E^2

(e_o is my way of saying epsilon not)

So I rearranged to solve for E

E=sqrt(I/c*e_o)

The answer I get is 45.5.... but its not correct?

Any Suggestions?

vector diagram

cant figure out how to use that phaser diagram. How do i draw on it, and those two arrows that you are given to start off with dont move?

Conceptual Question

When Maxwell proved that c, the speed of light, was equal to 1/sqrt(epsilon_0 x mu_0) he had proven something monumental. Why?

Helpful?

Does anyone ever go on this blog anymore? Are you guys finding it helpful or is it not really working out? This is the first semester I am trying this out on and so I am wondering if anyone is really using it or not. Let me know. Thanks