The End of Year Exams are coming and I need to start revision very soon! So, I feel that I should run through the topics that I have learnt in the entire year, and where else can I do it but on my ePortfolio!
Term 1 :
In Term 1, we focused more on chemistry, which consists of the atomic structure, electronic configuration, different compounds, the periodic table and so on. Back then, I still remembered how tiring it was to remember all the different elements in the periodic table, but fortunately, in the test we were only tested on the first 30 elements. However, in the end of year exam, we are required to memorise the whole periodic table, and that is one point I do have to take note! We also learnt how ions are formed. Personally, I feel that as long as we understand the theory behind the formation of ions, and have the knowledge of the number of electrons each element has, this should not be a problem. One thing I have to revise thoroughly is the drawing of the full electronic configuration of ions. Sometimes, we can carelessly leave out one or two details, such as the dots and crosses we indicate as electrons, and that can cost us the mark, which was what happened in my test as well. I just hope that I can revise well for chemistry and not make the same mistakes as the ones in my worksheets and test, for it will be such a regret to do so.
Term 2:
We entered of acids and bases and I find that topic relatively interesting. Perhaps, the difficult part to some is the memorisation of how acids and other substances react to one another. But I find that it has much to do with what we experience in our lives, like whether bee stings are acidic or alkaline, and the different types of acids that are present in the fruits we eat.
Another topic we entered was light and we had to learn the characteristics of a plane mirror. Honestly, as mentioned in my previous post, I had very little interest in this topic, but anyway, we should not go into that. For me, the most challenging part of this topic is the drawing of ray diagrams, with the application of the knowledge we have learnt. Sometimes, when I am just so engrossed in drawing the diagram, my mind blanks out and I cannot think of anyway to apply the knowledge I have learnt. I have to train myself to stay calm whenever I am faced with these questions, especially in the EOYs.
Term 3 :
We finally entered the last sub-topic for light, optic lenses. Initially, I had a difficult time trying to put all the characteristics of the image formed by an object at different positions when in front of an optic lens. But after some time, I realised that everything had all become so natural, and I am glad! So I did not face much difficulty doing the questions related to that topic. For Term 3, the difficult part was Ecology, as if the towering numbers of biotic and abiotic factors were not enough, there was still other portions such as the carbon cycle and conservation. However, in the test, there was a question which was about a place in a foreign country and we were tested on ecology in relation to that place given its description. This question has reminded me that Science, especially Ecology, is not all about memorisation of knowledge, because Science is everywhere in our lives, and we should not narrow our scope of knowledge purely on textbook knowledge.
I do hope I can complete my revision well and be ready for the end of year exams, because I really like Science!
Friday, September 9, 2011
Wednesday, September 7, 2011
A Personal Work Sample
I have decided to put in one of my ACE assignments as my personal work sample and improve it. Although I was awarded marks that were satisfactory, I thought that I could further improve this ACE in many other ways. So, this is one of the ACE I embarked on, "Refraction in our eyes".
Firstly, I explained how our eyes work. As light from the object we are looking travels from air to our cornea, it refracts, and actually, the largest percentage of refraction is done by the cornea, 80%. The other 20% is done by our lenses. After this, the refracted light is focused on the retina, which is the tissue that lines the inside of the back of the eye. In the retina, there are photoreceptors, which consists of cones and rods. Cones are sensitive to colour while rods control our black and white vision in low-light conditions. Finally, these images are transmitted through the optic nerves to our brain for interpretation.
Now, I will explain the refractive errors our eyes may have, one of which is far-sightedness. As usual, the light is refracted as it passes through our cornea and lenses, and is focused on the retina but in the case of people with far-sightedness, the light that is refracted is not focused before it reaches the retina, which causes a blurred image.
In other cases, there are people with near-sightedness. Instead of the light focusing on the retina, or focused only after it reaches the retina, the light is focused even before it reaches the retina. This causes a blurred image as well and is what we call near-sightedness.
Reasons for refractive errors
Far-sightedness
The three reasons for far-sightedness are short eyes, flat curvature of lens and irregular shape of our cornea. Short eyes will result in the light being unable to be focused on the retina by the time it reaches it. Flat lenses and irregular shape of corneas will distort the angle of refraction of the light that enters our eyes, causing the same effect of having short eyes.
Near-sightedness
The three reasons for near-sightedness are long eyes, steep curvature of lens and irregular shape of cornea. Conversely, long eyes will result in the light being focused before it reaches the retina. Similarly, steep lenses and irregular shape of corneas will distort the angle of refraction of the light that enters our eyes, causing the same effect of having long eyes.
As we evaluate the causes of refractive errors, we can conclude that there are 3 factors that causes these problems, our eye length, the curvature of our cornea and the curvature of our lenses.
Solutions to these problems
A very advanced way of solving these eye problems is undergoing LASIK surgery, which stands for LAser in SItu Keratomileusis. It consists of five steps.
Firstly, a suction ring is placed on the eye. Then after, a microkeratome is used to cut a partial flap in the cornea with uniform thickness. The flap is then folded back, exposing the middle area of the cornea. Laser pulses are then sent through the excimer laser onto the middle area of the cornea. After this is done, the flap is then replaced and the surgery is completed.
What the LASIK surgery actually does is to correct the shape of our lens, in relation to the refractive errors we are facing, so that our lens will not cause these problems anymore.
Another solution to this problem is using contact lenses. Concave lenses would solve the problem of near-sightedness while convex lenses would solve the problem of far-sightedness.
Near-sightedness (Note that the dotted rays are the rays that causes refractive errors while the non-dotted ones are the rays that undergo refraction through the lenses.)
Far-sightedness (Note that the dotted rays are the rays that causes refractive errors while the non-dotted ones are the rays that undergo refraction through the lenses.)
Reflections
This ace has reminded me of the importance of not leaving out any single detail when I am doing a project or an assignment, for they may mean a lot. For example, while doing this ACE project initally, I left out the explanation of how does LASIK surgery and contact lenses actually work, and this are actually the areas I can work on. I hope that I can learn from this ACE project and carry this attitude whenever I am doing ACE projects or assignments.
Sources --> Google Images
--> http://www.lasersite.com/lasik/index.htm
--> http://www.allaboutvision.com/eye-exam/refraction.htm
Firstly, I explained how our eyes work. As light from the object we are looking travels from air to our cornea, it refracts, and actually, the largest percentage of refraction is done by the cornea, 80%. The other 20% is done by our lenses. After this, the refracted light is focused on the retina, which is the tissue that lines the inside of the back of the eye. In the retina, there are photoreceptors, which consists of cones and rods. Cones are sensitive to colour while rods control our black and white vision in low-light conditions. Finally, these images are transmitted through the optic nerves to our brain for interpretation.
Now, I will explain the refractive errors our eyes may have, one of which is far-sightedness. As usual, the light is refracted as it passes through our cornea and lenses, and is focused on the retina but in the case of people with far-sightedness, the light that is refracted is not focused before it reaches the retina, which causes a blurred image.
In other cases, there are people with near-sightedness. Instead of the light focusing on the retina, or focused only after it reaches the retina, the light is focused even before it reaches the retina. This causes a blurred image as well and is what we call near-sightedness.
Reasons for refractive errors
Far-sightedness
The three reasons for far-sightedness are short eyes, flat curvature of lens and irregular shape of our cornea. Short eyes will result in the light being unable to be focused on the retina by the time it reaches it. Flat lenses and irregular shape of corneas will distort the angle of refraction of the light that enters our eyes, causing the same effect of having short eyes.
Near-sightedness
The three reasons for near-sightedness are long eyes, steep curvature of lens and irregular shape of cornea. Conversely, long eyes will result in the light being focused before it reaches the retina. Similarly, steep lenses and irregular shape of corneas will distort the angle of refraction of the light that enters our eyes, causing the same effect of having long eyes.
As we evaluate the causes of refractive errors, we can conclude that there are 3 factors that causes these problems, our eye length, the curvature of our cornea and the curvature of our lenses.
Solutions to these problems
A very advanced way of solving these eye problems is undergoing LASIK surgery, which stands for LAser in SItu Keratomileusis. It consists of five steps.
Firstly, a suction ring is placed on the eye. Then after, a microkeratome is used to cut a partial flap in the cornea with uniform thickness. The flap is then folded back, exposing the middle area of the cornea. Laser pulses are then sent through the excimer laser onto the middle area of the cornea. After this is done, the flap is then replaced and the surgery is completed.
What the LASIK surgery actually does is to correct the shape of our lens, in relation to the refractive errors we are facing, so that our lens will not cause these problems anymore.
Another solution to this problem is using contact lenses. Concave lenses would solve the problem of near-sightedness while convex lenses would solve the problem of far-sightedness.
Near-sightedness (Note that the dotted rays are the rays that causes refractive errors while the non-dotted ones are the rays that undergo refraction through the lenses.)
Far-sightedness (Note that the dotted rays are the rays that causes refractive errors while the non-dotted ones are the rays that undergo refraction through the lenses.)
Reflections
This ace has reminded me of the importance of not leaving out any single detail when I am doing a project or an assignment, for they may mean a lot. For example, while doing this ACE project initally, I left out the explanation of how does LASIK surgery and contact lenses actually work, and this are actually the areas I can work on. I hope that I can learn from this ACE project and carry this attitude whenever I am doing ACE projects or assignments.
Sources --> Google Images
--> http://www.lasersite.com/lasik/index.htm
--> http://www.allaboutvision.com/eye-exam/refraction.htm
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