Wednesday, February 15, 2012

Do Exams Matter

Do Exams Matter?
I am going to start with a Yes for the time being, and as the page turns, different ideas will be discussed. The exam mentioned here refers to academic exams.
Yes, exams do matter for a number of reasons. As far as education system is concerned, to be consistent with the rest of the class, exams are conducted with a common syllabus in mind to check if a student has grasped the essential contents of the subject.

An exam helps a student make a self estimate of his knowledge in the subject. It gives a student a goal, without which he might as well spend his time reading random stuff for knowledge. It helps teachers analyze their teachings in class, and make appropriate changes in their future lectures and standard mark with which academics can be measured.

However, exams only represent the on spot knowledge presented by a student in an exam hall, and not the over-all knowledge of the student itself. Most content that appears in an exam has to be covered in the class and exams should not contain out of the blue seeming topics (which is unfortunately, these days a quite common practice in most engineering colleges). Students must be challenged based on what is taught, and not on what the lecturer considers difficult to understand. It is also fundamentally wrong to expect every student to be a copy of Albert Einstein!!!

Though the fear of failure is a motivational drive for last minute studying students, it forms a definite goal for students who aim at topping the subject, because, in order to top an exam, the student tries to cover the entire syllabus well before the exam and this aspect alone can be the drive to gain more knowledge.

Scholarships and fee reduction for academically excelling students’ forms another motivational aspect while studying a particular subject.

How much do exam matter?
The answer to this question is purely dependent on an individual and depends on the scenario, on the individual’s motives and priorities in life. Additionally it also depends on an individual’s life experiences so this matter will not be addressed directly.

Before: an exam, it is the duty of the individual to make sure that he knows why he is writing an exam and has to know the syllabus of the exam. Make sure you study with an attitude of learning all that is recommended and aim for the top place.

During: an exam it is in the best interest of the student to be equipped with knowledge as well as accessories required for the exam. Punctuality for examination and carrying a wrist watch is recommended to make sure that the best use of the allotted time is made. For good recollection during an exam, a student has to make sure that he has reserved some time for a last minute revision just before the exam. And maintained all the required content of the exam in a well accessible format.

After: an exam the general tendency is to expect a very good result, regardless of the performance. However, ideally, it is best to get rid of all expectations and move on with another activity till the results arrive.

Effects of exam stress:
Exam stress can have several effects such as sleep deprival, nightmares, tension, under-esteem, lack of confidence, lack of concentration, poor recollection and other health issues.

Why are exams feared so much?
As children, parents tend to judge students based on their marks, and tend to compare with other children of that age or with a sibling. This is a very wrong practice and affects the students way of thinking as a whole.

Though failure at an exam is on top of the list of fears, the real fear of exam arises due to lack of effective preparation for the corresponding exam.

And the worst part is that the results of an exam is feared more than the exam itself. 

During school, i have never been forced to study, and neither had i done very well in academics, I used to talk a lot and get punished regularly and did not know the importance of education. How ever much much later i began performing well and found out that if your grades are good enough, the other person usually gets the blame of talking. So I advice study you to study well, there are several little benefits apart from the major ones like job selections and scholarships and gold medals.

My advice:
Prepare well when you have time, because no one knows how tomorrow is going to be. It is better to start sharpening the sword during peace, rather than after a battle has begun, as an old story says.

Sunday, February 5, 2012

Why Resistance halfens in parallel

Why Resistance halfens in parallel
A resistor offers resistance offers resistance to current. I have used the parallel resistance formula to solve an enormous number of problems in my B.E course on Electronics and Communication. However this question did not strike me back then; If a resistor offers a resistance R then why do 2 resistors in parallel offer lesser resistance? This question did not appeal to us probably because in most courses, resistors are learnt after capacitors and while learning, the teacher says that the two formulas (Resistors in series and capacitors in parallel) are similar and we buy it, and start applying it.

I was sitting in Udupi bus-stand waiting for my bus to Bangalore when this question struck me and it took some time for me to get the answers that night. I first tried approaching the problem in terms of the material used for the resistors, which according to me were both the same so it would not generally matter.

We learn in electronics that a voltage source appears to behave like a tank of water maintained at some potential.  The resistors in this case act like a pipe, whose diameter restricts the flow of water from the pipe to the ground.  So if 2 pipes are connected in parallel, then each pipe would still continue to offer the same resistance to the flow of water but would convey twice the amount of water to the other end. This realization was the key in understanding how resistors also appear to offer only half the amount of resistance to current in an electrical circuit. This can also be thought of as the cases where the two pipes are replaced by one thicker pipe to offers an equallent reduction in resistance.

In the case of Series circuits, however, the pipe would now be twice as long and the distance the water needs to flow doubles and hence the resistance offered by the effective pipe-chain, is twice as much. Hence resistors in series offer double the resistance.

This basic principle can be extended to any number of pipes in series or parallel and hence in resistors as well.

When I discussed this with my friend Ashish in Bangalore, he gave me his own point of view which was that each resistor continued to send the same amount of current across the circuit and hence the doubling of current meant a halfening of resistor value.

We can also look at the problem like a road. If there are parallel roads or one road with several lanes then the traffic can move faster and hence offers less resistance to movement. And if there is just one lane, then the traffic will be clogged and acts as series resistance.
To conclude, the behavior of resistors, pipes, traffic can be analyzed on similar grounds and it is important to know the significance, even though we can manage most situations in life continuing to be ignorant.

Note: We find a similar behavior in all places where networks are involved, such as human body circulatory system, water supply channels, road networks, truss networks, electrical networks, spider web, internet, structure of birds nest, etc. How ever I don't think it is necessary to discuss any of them in detail in this post.
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