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Wednesday, August 17, 2011

Physics Application: Electric Bell

Today's tips:One important aspect in studying physics is the ability to apply & relate each physics concept. In SPM application part is vital as it always being asked in paper 2. You are expected to explain certain physics application such as the working principle of an electric bell. Usually there are 4 marks allocated for this type of question. However to explain it, u must fully understand the physics concept being applied. In the case of electric bell, we apply the concept of electromagnet.Generally to understand basic concept of electromagnet, we must appreciate that every time current flows in a wire, magnetic field is produced. If the wire is coiled around soft iron, this causes the soft iron to be magnetized and become a temporary magnet. Once it becomes a magnet, it has the tendency to attract any magnetic materials such as iron armature in the bell.Once u understand the basic concept, then u must practise to explain the working principle of an electric bell. Why dont u take a reference book,watch this video.. try to undertand and explain how it works ..There are many other application of electromagnet such as relay switch,telephone ear piece, circuit breaker etc. Just make sure u are able to explain all of them.

Tuesday, August 9, 2011

DEFINITION

Today i'm going to discuss on SPM physics definition that can come out in paper 2 section A, B or C. Although there are a lots of definition need to be memorised, in average only 3 to 4 definition will be asked in the exam. Each definition contributes one mark only. If u are aiming for A+, u cant afford to loose too many marks. So its up to u, whether u want to grab all the marks on definition or to 'sedekah' some of them :)

Some definition can defined straight forward by referring to its formula. For example, pressure can be defined as Force acting per unit area ( P=F/A) or resistance can be defined as ratio of potential differnt over current (R=V/I).

However please be careful because not all definition can be defined based on its formula. For example u can't define potential different by using V=IR. If u say that potential different equals to product of current and resistance, u 'll lose the mark. In fact to define it, u should refer to its fundamental equation, i.e V=E/Q. Thus potential different is defined as 'energy needed to move a unit charge from one point to another'.

Some of the definition does not belong to any equation. For example elasticity is defined as 'the property of an object that enables it to return to its original shape after an applied external force is removed'
This kind of definition will be easier to memorise if u fully understand the keyword used to describe it. Basically once u can understand the physics concept being discussed, its much easier for u to memorize the definition.

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