Wednesday, January 19, 2011

Hello everybody! Today's class consisted of answering the three worksheets we received the previous day, so I'll go ahead and post up the answers!


Transparency 25-2 Worksheet
" AC Generator"

1. As a wire moves through position 1, how is it moved with respect to the magnetic field?
- The wire is moving perpendicular to the field.

2. How much current is carried through the wires as it moves through position 1?
- Max amount of current, Imax.

3. As the wire reaches position 2, how is it moving with respect to the magnetic field?
- The wire is moving parallel to the field.

4. How is the change is the orientation of the wire in the magnetic field related to the amount of current induced in the wire?
- Only the component of motion that is perpendicular to the field induces a current.
Position 1 & 3 - Max I (current)
Position 2 & 4 - zilch

5. How much current is carried through the wire as it moves through position 3?
- Imax.


Transparency 25-3 Worksheet
"Lenz's Law"

1. What is the direction of the current induced in the wire as a result of moving through the magnetic field? What rule is used to determine this direction?
- Induced current ia downwards, using the 3rd right hand rule.

2. How does the direction of the force exerted by the magnetic field on the wire related to the original motion of the wire?
- Force exerted by B opposes original motion of wire.

3. What is Lenz's law?
- It states that the direction of the induced current is such that the magnetic field resulting from the induced current opposes the change in the field that caused the induced current.

4. If the generator produces a small current, will the armature be easy or hard to turn? Why?
- Easy to turn, the opposing force on the armature is small.

5. Why does placing a mechanical load on a motor cause more current to be carried through the motor?
- The rotation of the motor slows. The slowing decreases back EMF and allows more current to be carried through the motor.


Transparency 25-4 Worksheet
"Step-Up and Step-Down Transformers"

1. In the step-up transformer, the primary coil has two turns, and the secondary coil has four turns. By what factor is the voltage in the primary circuit stepped up by the transformer?
- Vp/Vs = Np/Ns = 2/4 = 1/2
2Vp/Vs = 1/2
Doubles Vp

2. If the voltage across the primary circuit of the step-up transformer were 120 V, what would be the voltage across the secondary circuit?
- Vs = Vp.Ns/Np = (120 V)(4 turns)/(2 turns
Vs = 240 V

3. If the voltage across the primary circuit of the step-down transformer were 350 V, what would be the voltage across the secondary circuit?
- By not knowing the number of turns on the primary or secondary, you cannot calculate Vs.

4. If the current in the primary circuit of the step-down transformer were 40 A, what would be the current in the secondary circuit?
- Increase I (current) on the secondary circuit, but can't calculate accurately due to not knowing both voltages.

5. If the voltage in a transformer is stepped up, the current has been stepped down. Ohm's law indicates that increase voltage typically produces increased current. Explain this seeming contradiction.
- Ohm's law holds true in a single circuit. In this instances, the current being compared are actually in two different circuits.


Chapter 37: Electromagnetic Induction
"Transformers"

1. What will be the voltage output of the secondary?
- 1200 V

Vs = Vp.Ns/Np

2. What current flows in the secondary circuit?
- 1.2 A

Is = Vs/R

3. Now that you know the voltage and the current, what is the power in the secondary coil?
- 1440 W

Ps = Is.Vs

4. Neglecting small heating losses, and knowing that energy is conserved, what is the power in the primary coil?
- 1440 w

5. Now that you know the power and the voltage across the primary coil, what is the current drawn by the primary coil?
- 12 A

Ip = Pp/Vp

6. (up)(down)
7. (more)(less)
8. (voltage)(energy and power)
9. (step-down)(20/1)
10. (ac)(continually change)

Finally, filling out the last of our chapter 25 Study Guide!

Self-Inductance

Current generates a(n) magnet field, creating new field lines, which cut through the wires. As a result, and EMF is generated and it opposes the current change. The faster you try to change the current, the larger the opposing EMF, and the slower the current change. Because of this self-inductance, work has to be done to increase the current that flows, and the energy is stored in the magnetic field.

Transformers

A transformer is used to increase or decrease AC voltage without a loss of energy. A transformer contains two coils that are insulated electrically from each other, but that share the same core. When the primary coil is connected to a source of AC voltage, the changing current creates a varying magnet field. A varying current is induced in the secondary coil, by the process of mutual inductance. The ratio of primary and secondary voltages depends on the ratio of the number of turns in the two coils. I a step-up transformer, the primary voltage is less than the secondary voltage, and the current in the primary circuit is greater than the current in the secondary. In a step-down transformer, the primary voltage is the secondary voltage and the current in the primary circuit isgreater than less than the current in the secondary circuit.

Now after all that we received 3 more pages!

Chapter 26 Review
Transparency 22-4 "Electric Power Transmission"

And last but not least THE EXAM REVIEW ANSWER KEY!

Don't forget to pick those up and FAST! Especially the Answer Key. I'll upload that as soon as I can. (Too lazy to change computers.)

Less than, but about, 2 more weeks until exams! Studystudystudy, and an expected test (our last!) on Tuesday. Good luck everyone!

Tuesday, January 18, 2011

Hello my fellow classmates. I am back to compensate for yesterday's scribe. During yesterday's lesson, we had watched a video on electromagnetic induction and alternating current. Along with that video, we were given questions to answer while watching the tape. I will attach a link to the question sheet and the answers to it at the end of this post. After watching the video, we were given 3 other hand-outs called "Transparency 25-3," "Transparency 25-4," and "Transformers." If you missed those hand-outs, please see Ms. Kozoriz for them.

We also discussed about some interesting news about our province has been selling hydro to the U.S.A. This connects to the topic of Alternating Currents (AC) where it can be transported over large distances/areas. Our province has been earning a large amount of profit from selling hydro to America.

Anyways, here is the video question sheet for those of you who didn't receive a copy.

ELECTROMAGNETIC INDUCTION/ALTERNATING CURRENT VIDEO WORKSHEET:

Here are the answers for the questions:

ELECTROMAGNETIC INDUCTION:

1.) A flow of current for a magnetic field

2.) Hans Christian

3.) Michael Faraday

4.) No

5.) First electric motor

6.) When there is a change in the magnetic fields

7.) F = Bqv (F = Force, B = Magnetic field, q = charge, v = velocity)

8.) Loop moves away from current, loop moves towards current, magnet moves away from current, magnet moves towards current

9.) Yes

10.) Number of field lines per area

11.) Zero

12.) Phi

13.) Yes

14.) Yes

15.) Current induced creates a magnetic field of it's own

16.) Yes

17.) Change the magnetic flux

18.) Electricity and magnetism

ALTERNATING CURRENT:

1.) Emigrated from Eastern Europe, he knew 12 languages

2.) Moving back and forth

3.) Alternating current

4.) Direct current, Thomas Edison

5.) He invented the phonograph, motion picture camera, and telegraph

6.) AC can be transported over large distances

7.) A small current, large voltage

8.) Using transformer to send power to large distances

9.) Raises and lowers voltage

10.) Yes

11.) Heat, distance, current small, voltage high (I^2 x R OR P^2 x R/V^2)

12.) Generators are needed for far distances

13.) Edison didn't like Tesla

For those of you who missed some of the answers, here you are :)!!! If there are any mistakes, please correct it by leaving a comment. If you are unsure about the answer, please see Ms. Kozoriz.

As for the whole class, not much was taught yesterday. For those who were absent, you didn't miss anything important. Remember to study for our physics exam that is in 13 days!!! Our next test will be on Monday, January 24, 2011. So get ready to do some studying!!! Thanks for reading my post :), hope you all have a great night!!!

Monday, January 17, 2011

We started today's class by going over last week's homework, Transparency 25-1 and Electromagnetic Induction.

For Transparency 25-1 Worksheet, the answers are:
1. Electrical energy; battery
2. Rod with a wire coiled around it; magnetic force created by the field magnet
3. N and S poles will reverse
4. Mechanical energy from the crank
5. Electromagnetic induction as the wire moves through the magnetic field
6. EMF increases

For Electromagnetic Induction, the answers are:
1) 0.97 V
2) 1.9 x 10^-3 V
3) 0.020 V
4) 1.0 x 10^-4 V
5) 3.74 V
6) 50 turns
7) 1.8 V

Later on in the class, we also went over Lenz's Law on the Chapter 25 Study Guide. The answers for this are:
- direction
- flux
- current
- armature
- increases
- back-EMF
- decreases
- decreases

Lastly, we received a couple of handouts; Induced EMF/Factors Affecting Induced EMF, a graph of induced potential difference vs time, Lenz's Law, a worksheet to practice Lenz's law and Transparency 25-2.

Please have the worksheet for Lenz's law and Transparency 25-2 done for homework.

-- Rainer

Wednesday, January 12, 2011

Hey grade 12's!

Today we went over the duck textbook questions, we were assigned on Friday when Ms. K. was away. The questions that were assigned were 35. a) - d) 36, and 37 on pages 622 - 623. We also went over the worksheet that was handed out to us on Monday called Combination Circuits. The rest of the class was used to finish our Circuit Booklet Assignment or work on the physics exam review or study for the test.

TEST TOMORROW, GOOD LUCK!

Series, Parallel and Compound Circuit

Hiii everyone,  today we started with Study Guide and went through following answers:

1.b
2.c
3.d
4.a
5.a
6.b
7.b
8. charges conserved
9.Vb=IRb
Vb=(VRb/Ra+Rb)
10. series circuit
11. gives proper amount of voltage
      we dont need to worry about 12 and 13.
14.b
15.c
16.b
17.a
18.a
Applications of circuits:-
1. true
2. false
3. false
4. true
5. false
6. false
7. a
11. ammeter
12. series
13. low
14. voltmeter
15. parallel
16. high
    We got worksheet about compound circuits.
1. R= 2.5
2. R= 4
3. R=1
4.a) Resistance= 2
P=I.V=8w
Resistance=4
P=16w
Resistance=6
P=24w
b) Resistance=1
P=4w
Resistance=2
P=8w
c) Resistance=6
P=6w
Resistance=3
P=12w
      Question 4(d) is homework which is due for tomorrow. We also worked on worksheet Series and Parallel Elements and we have an assignment on three circuits which is due on Monday 01/10/11.

Friday December 17

On Friday we received new notes on Circuits;
-Transparency 32: Circuits and Circuit Diagrams
-Transparency 33: Series Circuit/Parallel Circuit
-Study Guide 23: Simple Circuits

We also watched some videos on Parallel and Series Circuits as well as a demonstration
Here is a video similar to the demonstration we had:
http://freecircuitdiagram.com/2010/04/04/electricity-series-parallel-circuits-video-tutorial/

We also got our Electric and Magnetic Field tests back. Remember to do your corrections and hand them back in to Ms. Kozoriz.

December 16

Today we started the new unit by looking at Ohm's law and circuits. We also examined circuit diagrams and the symbols that can be found on them and were then assigned a worksheet called Circuit Symbols which we went over in class. A second worksheet, Resistivity Problems, was assigned. This assignment is homework if you didn't finish it in class.

Electric and Magnetic Fields

Hi Guys! today we started class with the questions given by Miss Kozoriz yesterday from the duck book.

75. d=5cm/100=0.05m
E=5.10^3 N/C
V=E.d=2.5.10^2 V

76.
a) F=E.q=5.0.10^-4N
b) Ek=EP
EP=qV
V=Ed
V=(50)(1.0)=50V
EP=(10^-5)(50)=5.0.10^-4J
c) m=2KE/v.v=1.6.10^-12 kg

77. delta E= E2-E1=k q1q2/R2-k q1q2/R1=-2.08.10^-19 J

79.
a) q=W/V=1.8.10^-3 C
# of electrons=1.10^16 electrons
b)v2= under root qV/m=6.6.10^-23

80.
a)a=3.0.10^10 m/s. square
b)v=1.2.10^-15 J

81. R=1.9.10^-14m

82.
a)delta dh=0.00025m
b)v=6.0.10^6m/s

90.
a) Fe=Fg
Fe=mg
E=v/d
q=Fe/E
=mg/v/d
=mgd/v
=4.2.10^-19C

91.
a)v= under root 2qv/m=1.2.10^7m/s
b)v=under root 2deltaEe/3m=7.26.10^6m/s

                               As we've test tomorrow so we reviewed all the topics about Magnetic and Electric Fields. We have test tomorrow on Electric and Magnetic Fields so be prepared and good luck

Electric and Magnetic Fields

Hey Classmates we started from "Moving Charges Worksheet" 

and we went over problem 8 to 11 in the class.

8.v=2.1 . 10^5 m/s

   f=5.6 . 10^-13 N

   B=f/qv

   B=5.6 . 10^-13/(1.6 . 10^-19)(2.1 . 10^5)

   B=16.6T[left]

9.v=8.6 . 10^4m/s

    B=1.2T

    F=?

    F=Bqv

    F=(1.2 )(1.6 . 10^-19)(8.6 . 10^)

    F=1.7 . 10^-14N[E] 

10.v=5.0 . 10^5m/s

     F=4.0 . 10^-6N

     B=F/qv

     B=4.0 . 10^-6/(1.6 . 10^-19)(5.0 . 10^5)

     B=5. . 10^7T [out of the page]

11.v=2.0 . 10^6m/s

    B=5.0 . 10^-2T

    F=4.8 . 10^-14N

    q=?

    q=F/Bv

    q=4.0 . 10^-14/(5.0 . 10^-2)(2.0 . 10^6)

    q=4.8 . 10^-19C

Miss Kozoriz explain a bit The Mass of an Electron, we read the Green book from page 536-541 for some basic formulas.

We got home work for the Worksheet "Moving Charges" for problems 12-16 and Review Chapter 27. And we have test on Tuesday. Have a nice weekend and prepare for the test.

Wednesday, December 8, 2010

Hi hi guys! I am back with another scribe post for today. In class today, we first went over the two worksheets that were handed out on Monday called "Electric Potential" and "Physics 40S Electric and Magnetic Fields Assignment." Please click on the picture to see what the worksheets look like if you've missed it. You can ask Ms. Kozoriz for a copy if you didn't get one. If you want to see the steps on how to solve the problem, please come see me :). Otherwise, here are the answers for the worksheets if you can't read my writing:

Electric Potential

1.) 31 J/C (electric potential)

2.) a.) 3.6 x 10^-14 J (potential energy)

b.) 180 J/C (electric potential)

3.) 20,000,000 m/s (velocity)

4.) 3.0 x 10^-4 J (work)

5.) a.) 12 ev (work)

b.) 1.92 x 10^-18J ; 12 ev (energy)

c.) 2.05 x 10^6 m/s (speed)

Physics 40S Electric and Magnetic Fields Assignment

Part 1

Part 2

1.) a.) 3.2 x 10^-15 J (potential energy)

b.) 3.2 x 10^-15 J (kinetic energy)

c.) 8.38 x 10^7 m/s (velocity)

d.) 2.4 x 10^-10 s (time)

e.) 500,000 N/C (electric field)

f.) 8.78 x 10^16 m/s^2 (acceleration)

g.) 2.1 x 10^7 m/s (velocity)

h.) 2.5 x 10^-3 (displacement)

If you have any questions about the answers please come see me :).

Next in class, we were given 3 handouts. The handouts are "Moving Charges Worksheet," "Magnetic Formulae," and a cathode ray diagram that we previously got on Monday. Please click on the pictures to view the handouts.

Moving Charges Worksheet

Part 1

Part 2

Magnetic Formulae

Cathode Ray Diagram

It will be most likely that we will be correcting "Moving Charges Worksheet" tomorrow in class so for those who were in class please have it done and for the absentees, please see Ms. Kozoriz to get a copy.

Basically in today's class, we spent our time correcting the worksheets and were to work on the new ones that were handed out. New material was not taught in today's class so nothing important was missed. If you have any questions, please see Ms. Kozoriz or myself and we will be glad to help you.

Thanks for reading my post :)!

-Amy

Another scribe post FROM THE PAST (December 3)

By now I can't quite remember exactly what happened in class last friday, but that's why we have imaginations, right?

What I do remember however is going over question 5 from page 420 and questions 15, 16, and 19 from page 428, all from the green textbook. We went on to do a lab on charges, energy, and voltage. For homework we were assigned Electric Fields and Potential and the lab if it wasn't finished.

Hey classmates, today we started with Electric Potential 33-2 worksheet. We hand in our lab sheet and then Ms.Kozoriz explained Electron Volt and Equipotential line. We also discussed "Potential Energy and Kinetic Energy between two charged plates" worksheet. After  that we got 3 worksheet to work on; Appendix 2 -Fields (Illustrative examples), The physics of Cathode Ray Tube and Electric Potential. We'll hand these worksheets on wednesday. Thats all what we did in class.

  Have a great evening!

Scribe post FROM THE PAST (november 30)

Today, we started the unit on electric and magnetic fields by taking a look at Coulomb's Law. Coulomb's Law is simply a way to explain the force acting on one or more small charged objects called point charges by way of calculating the magnitude of the force (or forces) using the formula:



We were then assigned two sheets: one called Coulomb's Law for the sole purpose of better understanding the concepts of the new unit, and another titled Electrical Forces as practice applying this formula that we have definitely not seen in a similar form at any other point in our entire lives.

Wednesday, December 1, 2010

In today's class, we first went over the worksheets COULOMB'S LAW (the one where you had to underline the right answer) and ELECTRICAL FORCES.

For COULOMB'S LAW the answers are:
1-b. attraction
1-c. greater, less, 1/4 as much
2-a. doubled
2-b. quadrupled
2-c. quadrupled
2-d. 16 times

For ELECTRICAL FORCES the answers are:
1. -3.6 x 10^10 N (use Fe=kq1q2/R^2)
2-a. 7.80 x 10^-47 N (use Fg=GMm/R^2)
2-b. 8.80 x 10^-8 N (use Fe=kq1q2/R^2)
3. 2.5 x 10^19 electrons (use charge/e)
4. -1.76 x 10^8 C (use given mass/mass of electron)
5-a. 1.76 x 10^-15 N (add the force of each charged objects)
5-b. 2.63 x 10^11 m/s^2 (use a=Fnet/m)

Next we read through our first handout Coulomb's Law in One Dimension, Two Dimensions: Equilateral Triangle, and Two Dimensions: The Square.

To solve problems in one dimension, simply add the charges (like vectors). Don't forget that like charges repel and unlike charges attract.

To solve problems in two dimensions, first find the x and y components of each charge and add them together. Then combine the totaled x and y components by using the pythagorean theorem.

** Like vectors, electrical forces have direction.

Lastly, we were given question 5 on page 420 and questions 15, 16 and 19 on page 423 of the green books for homework!

Last Friday November 19

Hey guys, sorry about the delay, I forgot

We worked on several sheets that were given to us including
- a review on Gravitational Potential Energy
-Gravitational Fields Worksheet
-Escape Speed

Sample Question from "Gravitational Potential Energy Questions"

A 500.0 kg communications satellite is initially at rest on Earth's surface before it is launched into space. What is its gravitational Potential Energy at this point?

Use Formula PEG= - Gm1m2/R
G= 6.67 x 10^-11
m1 = 50.0kg
m2= 5.98x10^24kg (mass of Earth)
R= 6.37x 10^6 (Radius of Earth)

- [(6.67x10^-11)(50.0 kg)(5.98x10^24) / 4.22x10^7m]

PEG= -3.13 x 10^10


If there are any questions or you need the sheets from Friday feel free to ask Mrs. Kozoriz

Sorry again for forgetting about it :P

The gravitational potential energy

Hi everyone,

On Thursday we learn some interesting facts about GPE that equation of PEG = -Gm1m2/R is always produces a negative value.As R increases,the masses get further apart,PEg increases by becoming less negative.As R increases to the point of approaching infinity R → infinity,the potential energy approaches zero,PEg → 0

The differences between

FGand EGPE

1. F inversely 1/R square E inversely 1/R

2. is a vector quantity is a scalar quantity

3. S.I unit measured in Newtons S.I unit measured in Joules

Janna's Scribe Post for November 16th 2010 !

Hey guys for today's class we got back our Energy in a Trebuchet worksheet & our questions 3, 4, and 5 that we were to do out of the Green Textbook.
Next we went over our Chapter 8 Study Guide and filled in the blanks in the Universal Gravitation, Newton's Use of His Law of Universal Gravitation & Weighing Earth paragraphs on the first page of the study guide. The answers can be found in the slide post directly below my scribe on the first page of Mrs. K's post. Then we went over the answers of the first three pages in the Chapter 8 Study Guide Motions in the Heavens and on Earth booklet. Again, these answers can be found in Mrs. K's slide post from page 2 on.
After going over the answers we picked up 3 worksheets: Universal Law of Gravitation, Chapter 7 Transparency 7-2 & Chapter 7 Transparency 7-3. If you were away make sure you pick up these worksheets ASAP and do them for we will be going over the answers in class tomorrow. =)

Homework:
- Universal Law of Gravitation
- Chapter 7 Transparency 7-2
- Chapter 7 Transparency 7-3

Happy Homeworking !! :)

Monday, November 15, 2010

Hello my fellow classmates! It's me Amy scribing again. In today's class, we went over the problems in the green textbook that was assigned to us on Friday. The page number is 172 for those who missed the chance to do those questions. Questions 1-5 were assigned for us as homework and we had gonve over the first two in class today. The other 3 were to be handed in at the end of today's class. I'm assuming those are for marks so hurry up and hand them in before Ms. Kozoriz returns the assignments back to the class! I would give out the answers for question 1 and 2 but sadly they are on the same paper with the 3 other questions that are to be handed in. In other words, I don't have them with me :\. Sorry!!!

So for half of the class, we had worked on those problems. Afterwards, we were given 4 hand-outs from Ms. Kozoriz!!! Those hand-outs included "Concept-Development Practice Page (Chapter 12: Universal Gravitation)," "Chapter 11: Gravitational Intructions," "Issues in Space Exploration: Benefits," and "Chapter 8 Study Guide." Please see Ms. Kozoriz if you missed/don't have any of these hand-outs!!!

We had went over the "Concept-Development Practice Page (Chapter 12: Universal Gravitation)" and "Chapter 11: Gravitational Instructions" worksheet in class.

Here are the answers and what the worksheets look like:

Concept-Development Practice Page (Chapter 12: Univeral Gravitation)

--Check out the cool experiment in question 3!! You'll be amazed, guaranteed :D.

Chapter 11: Gravitational Instructions (Side 1)

Chapter 11: Gravitational Instructions (Side 2)

If you're wondering what "Fold" means, it means the solved equation equals to the "old force." The old force is the force we use to calculate our "Fnew" ("new force") for what we're trying to find. This correlates to having constants (number in front of "Fold") or no constant at all to determine the new force out of Newton's Universal Law of Gravitation equation. For example, if there is "4Fold" means 4 times the "old force." By increasing the "old force" 4 times, a new force ("Fnew") is developed where the it is equivalent to 4 times the "old force." Please see me if you don't understand the concept :).

Along with the other two hand-outs, we were to read the "Issues in Space Exploration: Benefits" package and finish the first 3 pages of the "Chapter 8 Study Guide."

There was not much work to do in class today. So for those who were absent, you guys didn't miss much. That concludes the lession in today's class. If anyone has a question about the hand-outs, you can come see me about any questions and see Ms. Kozoriz for the ones that you didn't pick up. As for a heads up in tomorrow's class, you guys will be receiving an additional 2 new hand-outs called "Transparency 7-2" and "Universal Law of Gravitation." Thanks for reading my post :)!!!

November 12, 2010

Hello everyone!

In physics class that day we had a lab about ellipses, pick the sheet up from Ms.Kozoris, and if any trouble ask a friend or Ms.Kozoris herself. It's not very time consuming so that's a plus!

Reminder that it is due to hand in ASAP!

We also had practice questions to do on pg 172 in the green physics textbook.

Friday, November 5th, 2010

During Friday's class, we went over and answered questions on the following sheets:
- Kinetic Energy (Transparency 11-1)
- Potential Energy at Varying Locations (Transparency 11-2)
- Grade 12 Physics: Work and Energy: Springs

We also received the following sheets:
- Chapter 10 - Section 10-1 Quiz
- Chapter 11 - Section 11-1/Section 11-2 Quiz
- Chapter 11 - Enrichment

The answers for 'Chapter 10 - Section 10-1 Quiz' and 'Chapter 11 - Section 11-1/Section 11-2 Quiz' are already posted so you may make your corrections. 'Chapter 11 - Enrichment' is due on Wednesday. Also a reminder, the Circular Motion and Work/Energy test in on Monday.

Goodluck!