Electromagnetism

Well today we worked on a sheet about right hand rules and also went over a magnetic field worksheet as well as other excersise questions.

Our test is tomorrow so here's a few things to remember.

First Right Hand Rule:

-Thumb points to the direction that the current flows.
-The other fingers point in the direction that the magnetic field circles in.

Second Right Hand Rule:

-This is used when you have an electromagnetic field.
- The iron core inside the coil increases the magnet's strength.
-The direction of the thumb points to the North pole of the magnet.
-The direction of the conventional current flow is indicated by the direction which the fingers curl.

Third Right Hand Rule:

-The thumb represents the direction of the current.
-The fingers represent the direction of the magnetic field.
- The direction of the force acting on the wire is represented by the direction of the palm.

Don't forget this equation:

B = f / IL

F is the force of the conductor in Newtons.
B is the magnitude of the magnetic field strength in Teslas.
I is the current in the conductor in amperes.
L is the length of the condutor in the magnetic field in metres.

Well that's it for me. Good luck on the test tomorrow and on the exam on Monday. Study diligently!

Good bye blog, good bye peers, see you next semester Ms. K!

Nature of Light

So today we went over questions 13 through 16 in class today. The answers can be seen in today's slides.
If there's anyone wondering what the orignal questions are, they go as followed:

13)When a screen is illuminated by two closely spaced parallel, single-filament light sources, no interference is observed. What major condition for interference has not been satisfied?

14) If Young's experiment was done completely in glass, how would the interference pattern change from that observed in air, using the same equipment and experimental set-up?

15) A student is measuring the wavelength of light produced by a sodium vapour lamp. The light is directed through two slits with a separation of 0.15 mm. The interference pattern change screen 3.0 m away. The student found that the distance between the first and the eighth consecutive dark lines was 8.00 cm. What was the wavelength emitted by the sodium vapour lamp.

16) An interference pattern is formed on a screen when a helium-neon laser light (λ= 6.328 x 10^-7 m) is directed towards it through two slits. If the slits are 43 μm apart and the screen is 2.5 m away, what will be the separation of adjacent nodal lines?

I realize that having answers without the questions aren't very beneficial.

We also did some reading out loud today as we read about the "Photoelectric Effect and the Wave Particle Duality."
It was Albert Einstein who proposed the idea that light is made of photons.
The Photoelectric effect itself refers to the ejection of electrons from the surface of a metal when it is exposed to electromagnetic radition. *as defined by our pink booklet.
To study this we would use a photocell that has two metal electrodes sealed in an evacuated tube. The air is removed so in doesn't stop the electrons from moving. The large eletrode is a cathode and coated with cesium or another alkali metal. The second electrode is an anode that is made of thin wire so it doesn't block radiation. To allow ultraviolet wavelengths to pass through the tube, it is often made of quartz. A power source is thus connected to the anode and cathode so that the negative side of the source is attached to the cathode and the anode on its positive side. The ammeter can measure the current flowing through the circuit. When radiation does not fall on the cathode, there is no current flow in the circuit. The current is due to electrons called photoelectrons being ejected by the cathode due to radiation and are attracted to the anode. The ammeter in the circuit can thus measure the current flow.

That's the basis of what we learned today. Then we were assigned to finish the last questions from the pink booklet.
Remember: Test on Wednesday! Good luck everyone.
That is all. Good day.

Straight Barrier: Wavefront

Hello everyone, this is Lina with today's scribe post.


We started today's class by going over the worksheet we recieved yesterday about wavefronts and wave rays. It was pretty straight forward.


Here are a couple of definitions for you:

A wavefront is a continuous crest or trough.
A wave ray is to show the direction of travel/transmission of the wavefront.
Remember: The wave ray is always perpendicular to the wavefront. You can also say that the wave ray is at a right angle to the wavefront.

For the wavefront exercise we had to draw the wave rays of circular, straight and irregular wavefronts.

We continued our unit, Waves in Two Dimensions. How exciting. Below is a diagram of how you would determine how the wavefronts are reflected at an angle to a straight barrier.

A few points to remember about this diagram are:

• The Incident wave ray is perpendicular to the Incident wavefront
• The Reflected wave ray is perpendicular to the Reflected wavefront.
• The normal is the straight line perpendicular to the barrier. (not in my diagram, but please bear with me)
• The angle of incidence (theta i) is the angle between the incident wave front and the barrier.
• The angle of reflection (theta r) is the angle between the reflected wavefront and the barrier.
• The angle of incidence is equal to the angle of reflection.
• Another thing you must remember is that the length between the lines of each wavefront should be equal in distance.

The diagram I drew above uses the angle of incidence and reflection as applied to the wavefronts to determine how the wavefronts are reflected.

Another method is to use the angle of incidence and reflection as applied to the normal. Therefore, the angle of incidence (theta i) would be the angle between the incident wave and the normal and the angle of reflection (theta r) would be between the reflection wave and the normal. I don't think we've used this method as of yet, but maybe we might later on.

We also looked at the reflection of waves from a Parabolic Reflector. We worked on drawing our own diagrams during the latter half of the class. We applied our knowledge of the straight barrier to help us out. The only difference is that it's a parabolic barrier.

Tonight's homework is our very first assignment in Waves of Two Dimensions. Complete it for tomorrow's class (or at least try to). ALSO don't forget our WAVES RESEARCH PROJECT due on September 25. Try not to leave it until the last moment like I know we've all done with one project or another. Good luck on that!

If you find anything confusing or anything wrong. Please leave a comment and let me know. This is my first time blogging for school where someone has to learn from it! I hope I didn't make any mistakes.

Last but not least, tomorrow's scribe will be... Mary Ann.