Thursday, January 27, 2011

Double Rainbow

It was raining again today..Due to heavy traffic jam, I arrived at school at 7am...It took me half an hour to drive from the main road to the school entrance which normally took only 2 minutes :(....Luckily my day was 'brighten' by my 2 dear students...Alvin 5Cekap & Salina 5Setia were on duty at the hall. Salina ask me to look at the sky...Wah! Amazing...i saw not only one but two rainbows! A double rainbow! Really hope this double rainbow will cheerish our day...Let today be better yesterday. Cheers!

The following pictures were taken by Alvin...Thanks to Salina & Alvin...for adding in my interesting collection of pictures...




 Author Donald Ahrens in his text Meteorology Today describes
 a rainbow as "one of the most spectacular light shows observed on earth".


The white light is a mixture of the colors of the visible spectrum. Black is a total absence of light.7 colours in visible light spektrum can be seen in a rainbow.  Each "coloured light" has its own wavelength and its own frequency, so we call it "monochromatic light" which means "light with one colour/one wavelength".
ColorFrequencyWavelength
violet668–789 THz380–450 nm
blue631–668 THz450–475 nm
cyan606–630 THz476–495 nm
green526–606 THz495–570 nm
yellow508–526 THz570–590 nm
orange484–508 THz590–620 nm
red400–484 THz620–750 nm



By the way, visible light is one of the 'member' of electromagnetic spectrum...We will learn this in subtopic 1.7. The following diagram shows the electromagnetic spectrum...observe where the red light lies...biggest wavelength in visible light spektrum.
Various wavelengths and positions of visible spectrum.



Tuesday, January 25, 2011

Principle of Superposition




PHASE DIFFERENCE VS PATH DIFFERENCE

Phase Difference
Phase is the relative position in the cycle. 
Each time that the process attains the same position its phase will have advanced 360 degrees.
 
Take as periodic process as a walking person, and place the start of phase when the right foot touches the earth. When the phase advances 180°, the left foot touches the earth. When the phase advances 360°, the right foot touches the earth.

Now take two persons walking beside. They start touching the earth with their right foot simultaneously: they are in phase, their phase difference is zero.

If they are parading soldiers they will stay in phase and their right foots will continue to touch the earth simultaneously.
But if they are not parading, the pace period of each one will be probably different. If the period of person B is shorter, his right foot will touch earth a little before person A. We say that person B is in advance on phase relative to A. Or that phase of A lags B. If the periods of each one stay so, the difference of phase will increase. Eventually B will be 180° in advance (or B 180° in retard).

When two waves have the same periodicity, that is same frequency, and travel at the same speed, if they travel the same distance they will keep the same phase difference. 




Path difference


Path difference is the difference between the actual lengths traveled by the two waves in space.
Suppose you send two light waves from two different points.
Suppose you send wave A horizontally on the x-axis and suppose you send wave B not perfectly horizontally but with some angle from some point on the Y.axis. These two waves will meet at some point on the X-axis. 
But the distance travelled by the wave A will be less than that by Wave B.
This difference in the actual path they took is path difference.



Thursday, January 13, 2011

1.1 Understanding Waves

 Voon created a simple 'trumpet' by using the concept of 'resonance'...
He forced the air in between the paper to oscillate with its own natural frequency...this result in the maximum vibration of the molecule, hence loud sound is produce...



5 Setia...happily observe the difference between the longitudinal & transverse wave...



Tuesday, January 11, 2011

1.1.11 Heavy Rain

Salam & Good day,


It had been raining since 3am this morning...The entrance to BL is flooded...
What a day to teach Chapter 1 Waves...can see ripple everywhere...


Welcome to My Fun Physics World especially to my dearest Form 4 student of SMKBL...not forgetting my Form 5 students...Welcome back to My Fun Physics World...


Really hope this year will bring us more joy, happiness and fun in searching new knowledge and experience...During lesson, don't hesitate to ask...Remember  "He who ask is a fool for 5 minutes...he who don't ask is a fool forever..."