The purpose of this blog is to help grade 12 physics students with problems and concerns in their course. Students should also reflect on the day's lesson - question, think, get curious!

Tuesday, June 19, 2007

Oh no!

Exams is in two days. Is everyone ready? My tip; study hard, look over the review sheet, all your tests, while taking 15 minute breaks each for each hour, and most of all, get an early nights sleep.

For the class on Thursday and Friday, all we did was study for the exam. However on thursday some of went to the UofM to apply for a scholarship. And in case you didn't know, if anyone has an average of 80% or above in atleast 5 classes from grade 9 to 12 are eligible. The scholarship qualifies not only for the UofM but Red River and UofW aswell. Talk to Mr. Purpur for more details, and be quick with it! First come first serve.

So I just wanted to wish everyone luck on their exams! GOOD LUCK! =)

Tuesday, June 12, 2007

Electromagnetic Induction Review

review for last fateful test! & CH 26 review

Chapter 26 review worksheet questions # 1-3 ignore 4&5 # 6-9
Answers on smart board

review for last fateful test! study hard everyone!
test out of 30-35 marks on Electromagnetic Induction including magentic flux, radius's, areas and diameters. need to know how to calculate these using the correct formulas.
A= (3.14)R2

Lenz's Law:
Know it!!
coil and magnet example

also need to know what a traansformer is.
Transformer- convert voltages
Pp=Ps means primary power = secondary power
IpVp=IsVs

Good luck on the test tomorrow and the exam next week

Friday, June 8, 2007

Scribe

Yay...I beat everyone to it. Today in class we started off with a video on Electromagnetic Induction and Alternating Current. The video was approximately half an hour. As we watched the video we filled out a sheet that was filled with questions about the video and we then went over the answers.

After the video we went over study guide number 25 and 26.

We then went over a worksheet titled Grade 12 Physics Worksheet: Electromagnetic Induction

Here are the questions and answers below
1. An airplane travels 1000 km/h in a region where the earth's field is 5.0 x 10-5 T and is nearly vertical. What is the potential difference between the wing tips that are 70 m apart?
EMF= Blv
EMF= (5.0 x 10-5 T )(70 m)(277.78 m/s)
EMF= 0.9722 V
2. A straight conductor 10.0 cm long is moved through a magnetic field perpendicular to the flux at a velocity of 75 cm/s. If the flux density is 0.025 weber/m2, what EMF is induced in the conductor?
EMF= 1.8x10-4 V
3. A rod 15 cm long is perpendicular to a magnetic field of 0.45N/(A)(m), and is moved at right angles to the flux at the rate of 30 cm/s. Find the EMF induced in the rod.
EMF= Blv
EMF= (0.45)(0.015 m)(0.3 m/s)
EMF= o.o2025 V
4. What EMF is induced in a 5.0 cm long wire moving with a speed of 10 cm/s across a field of 0.020 N/(A)(m)?
EMF= Blv
EMF= (0.020)(0.005 m)(0.10 m/s)
EMF= 1x10-4 V
5. A coil of 325 turns moving perpendicular to the flux in a uniform magnetic field experiences a change in flux linkage of 1.15 x 10-5 weber in 0.00100 s. What is the induced EMF?
EMF = 3.74 V
6. How many turns are required to produce an induced EMF of 0.25 V for a coil that experiences a change in flux linkage at the rate of 5.0 x 10-5 weber per second?
50 turns
7. A coil of 75 turns and an area of 4.0 cm2 is removed from the gap between the poles of a magnet having a uniform flux density of 1.5 wb/m2 in 0.025 s. What voltage is induced across the coil?
1.87 V

Class was almost over so we picked up 3 sheets, 21.2 Lenz's Law, Review chapter 26, and Transformers Chapter 37: Electromagnetic Induction. These sheets are to be done for Monday.

* Make sure you have a Physics Exam Review and the answer key.

I think that's it...so have a good weekend :)

Wednesday, June 6, 2007

Magnetic Fields

Hello Guys............(english,english).Ok what Ms. K discussed today is all about Magnetic Fields.

-One magnetic line is sometimes called Weber (Wb)

-units of B (magnetic field strength)

One Tesla(T)= one newton/(ampere*meter) or Wb/m2
-One Tesla is about 5 Times the strength of an ordinary bar magnet. The earth's magnetic field is about 5 x 10-5 T (0.00005)
-when we talked about the number of magnetic lines we use the expression Flux, and designate it by the Greek letter "phi"
Electromagnetic Induction
A current set op in a closed circuit located in a magnetic field whenever the total magnetic flux lining the circuit is changing.
Two conditions necessary for an electric current to be produced with a magnetic field:
1. Must have a closed circuit
2. Must have changing magnetic filed
Three factors that determine the value of the induced EMF are
1. Length of the wire
2. Flux density of the field
3. Speed of which conductor moves through field
and the formula....EMF=Blv
and after discussing all of this Jennie and her friend reported about mars exploration,it was supposed to be like past two months ago..
Next scribe would be.... nivram!!!hahahaah

Monday, June 4, 2007

Circuits Exercises

Hello guys!!!! Remember that we are having a test tomorrow so better read your notes tonight because it will help you have great test results. Back to what this blog is all about, Ms. K discussed the hand-outs she distributed last friday. The answers are posted in her slides. Afterwards, she gave us the answers to the exercises but the solutions are not given because she wants us to solve it ourselves. As a feedback, not giving out the solution is a good way to practice what we have learned because it will help us understand the topic more.
The following is from one of our hand-outs. I posted this because this what we need to remember and understand so that we can solve easy and difficult problems.

SERIES AND PARALLEL CIRCUITS

TYPE
OF CIRCUIT

1) SERIES

CURRENT is constant throughout the entire circuit.

POTENTIAL Individual potential drops add up to the total potential drop.
DIFFERENCE

RESISTANCE Rtotal= R1+ R2+ ....

2) PARALLEL

CURRENT Individual currents add up to the total current.

POTENTIAL Potential difference is constant across all parts of the circuit.
DIFFERENCE

RESISTANCE 1/R= 1/R1+ 1/R2+ ....

This table summarizes the basics about the series and parallel circuits so if you master this table, solving problems are not as hard as you think it is.

The next scribe is KEITH!!!!!!!!!!!!!!!!!!!!!

Good luck and Godspeed......(",)!!!!!

Resistivity and Combination Circuits