I think of the tree branches of science, biology, chemistry and physics, I am most interested and fascinated by physics, and I think that light is an interesting topic to start with. The laws of reflection and refractions are applicable all around us, for example everything you see around you is actually because of light rays reflecting into your eyes. What really confused me was the drawing of ray diagrams, which we all never done before. I did not really know why rays are drawn the way they are and how to even start drawing the ray diagram at times. Then I tried trial and error with all the worksheets I had and drew whatever I thought was correct based on my knowledge, then check and clarify with the answer key to clear any of my misconceptions. I soon realized that it was not as hard as I thought it was. In fact there are only a few basic rules you have to follow. First, the normal is perpendicular to the surface. Second, the angle of incidence is equal to the angle of reflection. Third, when a ray of light passes from an optically denser medium to an optically less dense medium, the light ray refracts away from the normal and vice versa. Forth, when incident ray is perpendicular to surface, there is no refraction. Lastly, the critical angle is the angle of the incidence ray from a denser medium to a less dense medium when the refracted ray is at 90 degrees from the normal or in other words on the surface, and if the angle of incidence is more than the critical angle, total internal refection occurs. It was very satisfying when I finally grasped the concept behind drawing ray diagrams.
In this term, I truly felt how lab lessons can aid me in my understanding of concepts. I did not actually know how converging lenses work until the practical lesson whereby we three beams of light to shine into a converging lens to see firsthand the effect it has on light. This made me understand better how a converging lens work, after being able to see how refraction occurs in the lens, and how moving the position of the lens affects the refraction of light. Another interesting lesson was when we had to observe the changes of the reflection of an object in front of a concave and convex mirror in relation to the object’s distance from the mirror. That lesson helped me in remembering how the image would be at different distances from the mirror, in relation to its focal point.
I think that I did badly in this term’s term test. I was so confident after the test that a high A1 was already in the bag, but in the end, well, it was not. In the end after looking through the paper I realized that the fact that I did memorize the content hard enough, coupled with poor time management were the combined culprit that cost me many marks. I did not memorize the chemical reactions between acids and ammonium salts, and also the charge of the ions (Sulfate or Sulfide). Apart from that I also did not memorize the PH levels and examples of weak acids, strong acids, weak alkalis and strong alkalis. Time management also cost me a lot as I was too obsessed with perfection in my ray diagram that I did not have enough time to do one or two questions at the back, which cost me a few marks too. I think there was definitely an improvement from the previous test in terms of carelessness, as I lost 1 instead of 5 marks because of carelessness. However that mistake was even more unforgivable as I went to memorize the number of electrons and the groups of the first 20 elements, and yet mixed up the valency and number of valence electrons of Nitrogen. This was definitely a horrible test for me and improvements can certainly be made. I hope this would be a wake up call for me to study harder for following science tests to get my A1 before I lose my chances of an exemption.
SUMMARY
REFLECTION AND REFRACTION
The normal is the line perpendicular to the surface. The angle of incident is the angle of the ray that hits the surface from the normal. The reflected ray is the ray that is produced when the light ray reflects off the surface. The angle of reflection, produced by the normal and the reflected ray, is always equal to the angle of incidence. When a ray of light passes from an optically denser medium to an optically less dense medium, refraction occurs, and the light ray refracts away from the normal and vice versa. When incident ray is perpendicular to surface in the same situation, there is no refraction. The critical angle is the angle of the incidence ray from a denser medium to a less dense medium when the refracted ray is 90 degrees from the normal, and if the angle of incidence is more than the critical angle, total internal refection occurs.
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