SPM tips: Learn how to Apply..

Learning application of each physics concept, principles or law is vital in order for u to do well in paper 2 section A,B &C. U should attempt at least 1 section B/C question every day..if u couldn afford to do it, at least do plenty of questions on sect A,B & C every week.

Some might asked ..what is actually a physics concept??
Pressure, impulsive force, momentum, total internal reflection are examples of physics concept that we learned in form4. Basically in SPM, for each concept u had learned, u must at least be able to describe its application.
For example..lets recall about total internal reflection..

In order for total internal reflection to occur, there are conditions need to be obeyed:
1. Light must travel from an optically dense medium to a less dense medium ( e.g from glass to air) 
2. incident angle (i) > critical angle (c)





Once u fully understood the whole concepts..its time to know where u should apply it. For this one, we can apply it in fibre optics. Thus its a must for u to describe how fibre optics work  based on total internal reflection concept. This video lecture might help u to understand it better..



If u wanna know more detail about fibre optics, u should watch this!

Are u studying last minute??

According to Charles Law,under constant volume when the temperature of the gas increase..its PRESSURE increases as well. The higher the temperature, the higher the pressure.

Yeah the hypothesis is so true epecially when we 're moving towards August 2010...The temperature is rising, day by day..& most of the form5 students are started to feel the heat. To make it worst..the PRESSURE is mounting as high as mount Everest . One of my student said.."Sir, i rasa nak muntah everytime nak revise..so many things to cover.sejarah lah..add maths, chem,bio..not to mention physics..
I answered him.."well thats the price for studying last minute :) " So if u are a form4 who accidentally reads this post...i hope u'll make a better preparation for 2011.

So  the big question mark now is how to study last minute???  Is it possible to get good marks??
For me its very subjective, it depends very much on how u handle the mounting pressure. I even had a student who fainted after knowing a BAD trial results..coz if u did it badly in trial, u have about a month to recover. It sounds so frightening right ;) but some of u couldnt be bothered coz at the moment they have this 'tak apa' attitude.


Let's imagine that u are watching a football match. There's only 5 minutes left before referee blow the final whistle. Suddenly u can see players of both team are so energetic. They start to work as a team.. chasing and passing the ball accurately. They are very focused & determined to get the winning goal. Finally the ball touches one of the net in a dying moment and a group of players chasing the goal scorer. Meanwhile the other team lie down on a grass with despair. It all happened in a very last minute of the game..

anyway ..Is it possible to 'score' if we study last minute??

If u analyse the football match.. One team managed to do it and the other one has failed.The same results goes to  last minute study.
So if u are doing last minute revision, make sure u stay focus & keep your mind in a positive mode.
Having study group also will help..as in a football match, u'll work better if u help each other. In football the coach helps them to set things right and for u guidance from teacher/tutor will be helpful..but its all rely on how good u are in handling the situation. The main principle for effective last minute study is to leave everything behind and set your study as your only priority. You can leave your problems with your friends, family and even forget about you don't even have a time to 'FACEBOOK' and play PS2. In the end, if u think positive..u can definitely make it!
Here some interesting tips for those 'last minute' students

SPM Physics: Logic gates

Yesterday i teach one of my weakest student   logic gates concept. He is the type who has problem to understand physics concept properly. Somehow, when i showed him a concept of logic gates, he tends to be addicted doing logic gates exercises... This shows that he is actually good in logical thinking.

Logic gates is actually a very simple concept learned in Electronics. In fact i can say that it is one of the easiest subtopic provided if u are able to think 'LOGIC' :)
However u need to understand the following basic logic gates i.e NOT,AND,OR,NAND and NOR.
U must be able to construct the truth tables for those gates. Truth table helps us to undderstand the behavior of the logic gates. In other words, it shows how the input of a logic gates relate to its output.

Usually students a are a bit blurred on this topic coz they wondered what is actually  '1' or '0' means?
keep in mind most of computerised devices work on electrical flow where a HIGH voltage is considered as '1' and LOW voltage as '0'. Logically, it is sorts of a switching system which requires some inputs in order to produce an output.



In SPM, u need to practise lots ofpaper2 questions on application of logic gates. Usually the question can be tricky..so u must really understand the condition explained in the application.
When actually they apply this logic gate concept??

Well i can give u a simple example.. if u used to wash your clothes using washing machine..we can create a LOGIC input for the machine which looks like this:
to rotate the motor, we need to fill in the water untill to a certain level. Once the water rises to that level..the input will be '1'... but some how it still not rotated...kenapa ya? Ops, may be you lupa nak tutup the 'top cover'. Here where the logic gates play its role..the rotating motor represents the output  which depends on the input of the water level & the 'top cover' position. So it needs both input to be '1', then baru dia rotate..
Thus we can use AND gate in this application.

U can Watch this video to improve your basic understanding on logic gates

Transistor as Control Switch

Today i'm going to continue our discussion about light control switch by using transistor & LDR.

Before we go further, firstly u must understand the characteristic of LDR?
LDR is a type of resistor known as Light Dependent Resistor which is very sensitive towards light.
Important point about LDR that u MUST remember:
In a BRIGHT condition, its resistance DECREASE
In a DARK condition, its resistance INCREASE.

Now lets have a look at the circuit below, describe what happen at NIGHT???
At night,

• LDR's resistance increase much higher than the fixed resistor,
• A higher voltage is supplied across the LDR,
• This increases the flow of base current and switch ON the transistor,
• The bulb lights up

So what if we want to switch ON the bulb in the morning & close it at night?
Its simple, u just need to change the position between the LDR & the 10k fixed resistor.

The same concept applies in Heat Control switch, except instead of using LDR we use THERMISTOR.
Again, its important for u to memorise the chracteristic of a thermistor, i.e;
HIGH temperature - Resistance DECREASE
LOW temperature - Resistance INCREASE

SPM: Transistor

This topic is a bit tricky, coz in SPM we didnt learn the actual details about transistor working principle and u   need to memorise certain facts. In order to understand a transistor, firstly u must get  to know its structure & terminal. Transistor has 3 terminals, i.e a base, collector & emitter terminal. There are two type of transistor, please make sure u memorize the different between them.

The first type is called N-P-N:

The second type is P-N-P:
Main function of a transistor is to amplify small current.So its a must for u to explain how does a transistor amplify the current.




Transistor as Current Amplifier:
Transistor is a component which relies on the current that flows in its base terminal.
A small changes in base current (Ib) causes bigger change in collector current (Ic).


The analogy is simple, if u attend  morning assembly in school..usually the teacher was talking using a microphone. What actually causes the teacher's voice become louder?? Is it the microphone alone??
Actually..its the amplifier which has a transistor that did the job to amplify the voice.
Please make sure u refer your reference book on its circuit arrangement as well as its experiment.

Transistor as a switch:
This part is important in SPM..u must be able to understand and memorise its circuit arrangement.
To switch ON the transistor, we need to have:

• a higher resistance in the base-emitter circuit 
• this causes a bigger voltage dropped across the resistor in base-emitter circuit
• In the end there's enough current flowing thru the base terminal to switch ON the transistor

i'll discuss detail abt this soon.....to be continued 

SPM Physics: Semiconductor Diode

In SPM, u must be able to describe semiconductor diode. How to describe it??

• When p-type & n-type semiconductor is joined together, a semiconductor diode is produced.
• At p-n jucntion, a depletion layer is formed when the electron from the n-type fill in the hole in the p-type.
• Connecting p-type to the +ve terminal and n-type to the -ve terminal causing the electron in the n-type to be pulled and filled in the holes across the junction. This movementof electron allow current to flow, thus the diode is forward biased.  
• When the connection is reversed i.e p-type to -ve terminal & n-type to the +ve terminal, the diode is reverse biased. Electron is pulled away from crossing the jucntion, thus no current is flowing.
• This shows that diode allow current to flow in one direction only.

Then u must appreciate the function of diode as rectifier. What is rectifier???

Diode as rectifier can convert AC current into DC current.

The process of conveting AC to DC current is known as rectification. There are two type of rectification that u need to understand in SPM. For each case u must hafal the waveform and its circuit connection. Lets analyse both of them;

1. Half wave rectification (refer to your book, then watch this!)

2. Full wave rectification (refer to your book, then watch this!)



After knowing the different waveform produce for those rectifiers..u also need to draw the waveform appear due to capacitor smoothing effect. Make sure u refer them back in your reference book.

Finally Its SPAIN!

I' m glad the World cup is over..now  i can have enough sleep :).. What also delighted me is that one of my favorate team was crowned as the champion . The way they played simply outclassed the Dutch . All their players were so calm & confidence in passing the ball. These players deseved the trophy coz they have a winning mentality.

Now the world cup is over, and its time to look forwrd for your trial & SPM preparation. For me, if u wanna score A+ in any subject, u must formulate the same winning mentality as what the SPain team did. U must be strong mentally..and always learn from your mistakes. The Spain team was beaten in a group stage, but they came back like an iron steel to reclaim their place as a favorate to win the trophy. They learned their mistakes, and always looked forward to win. In the end, they won it with flying colors. So..if u wanna really achieve an excellent SPM results..u must have this kind of positive attitude.

As usual i've observed some physics stuff being discussed among the commentators through out this word cup.If u noticed, in earlier campaign, the commentator kept saying the ball in South Africa bounced a bit higher than other places. For your info, most of the the stadium in 2010 world cup is located at a higher altitude.Thus it is observed that the ball bounce higher than usual .
Hmm...can u explain why the ball bounce higher as the altitude increase???

SPM Physics: Semiconductor

Basically,this topic wont be too difficult if u took chemistry in SPM.
As usual, u need to understand the meaning of semi conductor..

Lets start with the word 'semi' &  'conductor'..do u really understand what is conductor???Do u have any idea the word 'semi' is?? If u dont, i m not gonna give u the answer..take out a dictionary & start searching on your own..dont be lazy to THINK!!

So what is semiconductor??
Hmm again..Should i give u the answer??.. may b not!. coz its all in the text book or any reference book! I'm sure your parents have spent some money to buy a reference book for u..so why dont u learnt to USE IT!! I can bet most of your reference book, or exercise book are still looked neat & tidy as if u just bought it yesterday. So i think its time to do some 'conteng-conteng' on those books.Learning physics will be easier if u are not the type who is too lazy to think and  to reason logically ..but if u are the lazy type,frankly speaking its hard for u to get even a 'B'.
I might sound a bit harsh ..However dont take it too personal, bukan apa just to wake u up from your 'ignorance' attitude... at the same time i m trying my best to guide u to learn physics effectively.

Alright, lets get back to this topic..
How to describe semiconductors in terms of resistance & free electrons???
Usually pure semiconductors or intrinsic semiconductors are made from silicon or germanium. It conducts electricity when it has more free electrons especially under high temperature. However at low temperature, semiconductor produce few free electrons which makes it hard to conduct electricty. Thus the semiconductor acts as an insulator, i.e it has higher resistance.



So in simple words , semiconductor is actually a substance with its resistivity is between a conductor and an insulator. However u must bear in mind that its conductivity is not as good as conductor. So the question is,how are we going to make it a better conductor??

The answer is by having a DOPING process....hmm..What is DOPING????
It is a process to increase the conductivity of a pure semiconductor by adding an impurities.
In the end extrinsic semicondutors are produced.

There are two type of doping:

1. P-type

• p type is made by adding trivalent atom such as Boron
• trivalent atom has 3 electron in outer shell, one less than silicon.
• an extra hole is provided and this holes act as majority charge carrier for p-type

2. then we have a n- type :

•  it is made by adding pentavalent atom such as phosphorus
• pentavalent atom has 5 electrons in outer shell & 4 of them used to make covalent bond with silicon
• an extra unused electron  act as free electron which is the majority charge carriers for n type.

Sembang bola, sembang fizik

Senario 1:
Datang seorang anak kecil, hazim berumur 4 tahun menyapa pakngahya, Zahid:
Angah-angah..agak-agak siapa yang layak masuk 'final' world cup ni... hazim nak sangat tgk argentina masuk smpai final..
"Oh! sebelum masuk final, kena ada semifinal dulu..hazim"..sapa Zahid

Hmm tapi kenapa mesti ada "semifinal"..nama pun "semi"..lepas tu ..final".."semi" tu apa pakngah???
Terkedu sekejap zahid dengar soalan tersebut..lalu dgn spontan dia menjawab;
"Ala...'semi' tu semi lah..dah memang nama dia "semi"..ish byk tanyalah budak ni..Dah! pergi tidur"

Begitulah pertanyaan yang diaju oleh adik hazim...hmm kdg2 tidak terlayan telatah kanak-kanak yg sgt berfikiran kritis ..hampir semua perkataan ingin diketahui maknanya...NAMUN... 

Senario 2:
Pada keesokkan harinya, dgn mata kuyu zahid pergi ke sekolah dan dimulai dengan kelas fizik. Datang cikgu Tiara sambil mengedar kertas nota untuk diamati semua pelajar.
Sesudah itu cikgu Tiara bersuara:
Ok murid-mmurid, hari ini kita nak sambung berkenaan topik semalam iaitu applikasi semikonduktor dalam 'diode'. Saya harap awak masih ingat perbincangan semalam.."Baiklah,sekarang..buka muka surat..."
..sebelum sempat cikgu Tiara sambung bicara, Zahid bangun sambil bertanya dengan gaya 'blur'nya"..

Cikgu kejap..."semikonduktor" tu apa cikgu???
Dgn  geram..cikgu Tiara menjawab;
Kan saya dah terang semalam..semikonduktor tu datang dari 2 perkataan.."semi + konduktor"
Zahid jadi bertambah 'blur'..tapi cikgu 'semi' tu apa???

Ya Allah!...'semi' tu 'semi' lah zahid,.. budak sekolah rendah pun faham..takkan itu pun awak tak tau.Awak terlebih tengok "semifinal" ke malam tadi ???

Terus zahid tunduk tersipu-sipu dengan sindiran tajam cikgu Tiara.."Aduh, kalau lah aku tengok kamus bila hazim tanya, mesti aku tak jadi macam orang 'BLUR' pagi ini"..

Timbul rasa malu malu  kerana Hazim sekecil itu mampu meneroka kapasiti otak sampai  timbul rasa faham secara 'natural'...tapi aku ???? begitulah rungut hati zahid terhadap sifat "malas nak ambil tahu" yang semakin membarah, walaupun 'SPM' makin dekat...
Sambil merenung jauh, Zahid memujuk hatinya,
"Aku yakin mesti ada jalan..cuma aku mesti kena cuba, dan cuba..dan cuba !

CRO:Measuring Voltage & Frequency

Ok, today i'm gonna continue our discussion on Cathode Ray Oscilloscope. In last post i did mention one of the purpose using CRO is to measure voltage & frequency of a waveform.
To do this, we must understand the function of 'Y-gain & Time base'

Y-Gain:
- it is used to set the scales for the y-axis. Let say if u set the button at 10V/division..it means the y-axis has a scales of 0V,10V,20V,30V .....i.e each division has 10V.

Time base:
-meanwhile timebase is used to set the scales for x-axis. If the timebase is set to 10ms, i.e each division has 10miliseconds.

Now lets look at this video example,