Cathode Ray Oscilloscope (C.R.O)

To understand this topic, u must understand the following definition:

Themionic emission: - the release of electrons from a heated metal cathode

From the process of thermionic emission, we can produce cathode ray... By the way, what is chathode ray??


Cathode ray  defined as a beam of electrons moving at high speed in a vacuum.

This cathode ray concept is widely used in making TV. In SPM, we apply its concept in understanding the uses of Cathode Ray Oscilloscope.




Before applying CRO, u must understand the properties of the cathode ray itself. Make sure u hafal all those properties such as:
-moving in straight line
-negatively charged
-deflected by electric & magnetic field and etc.

Once u've understood & investigated all the properties..then lets have a look at the structure of the device called CRO:

Like it or not this chapter requires u to hafal all those structure of CRO. Besides that, u need also to memorise their function as they might be asked in the exam.


Then, u must understand the working principle of CRO and how to calculate the voltage + frequency of a waveform.

To calculate the voltage & frequency, u must understand to use 2 important button in CRO, i.e
'Y-Gain' & 'Time base'

...to be continued

Understanding Physics Definition

Usually in SPM, physics definition will contribute only  '1' mark...and through my experience, most of the students have gambled not to memorize any of them. However, wont u feel regret  if this 1 mark separates u between A & A+???

Memorising physics definition will be simple if u really understand the meaning of each word  used to describe it. For example, to understand pressure, it comes from the word "PRESS". 

Lets analyse this situation:

U have arrived at a friend's house, and  then u ring the bell.

Ringing an electric bell means u need to press the button. By pushing the button u are applying a force on its surface area.. as a result the button experiences a pressure from u...

Thus pressure is defined as force acting per unit area  (P=F/A)

Let me give u another example. I'm sure most of u are familiar with these words:
i. thermos
ii. thermometer
iii.thermal equilibrium
iv.thermistor

If u noticed, all the words above start  with a prefix "therm".. and all of them are related to a common physics concept called HEAT.
In other words, we can say that if the physics term start with prefix 'therm..' it has something to do with HEAT.

Lets discuss about another concept used in Elelctronics's chapter.  In SPM u must be able to define a physics concept called 'Thermionic Emission". In order to memorise its definition, u should understand the meaning of each word used.

Lets separate them into "Therm" + "Ion"  + "Emission"
1. It starts with the word 'therm'..thus as we know it has something to do with heat
2. then we have "ionic" which comes from the word "ion". For those who takes chemistry, the term ion will remind u about a process of releasing(emitting) or accepting "electron"

Now lets look at the real definition of thermionic emission:
-Thermionic emission is defined as the phenomenon of  electron emission from a heated metal surface-

For me, if u acquired the skill to interpret each word used to describe any physics definition, physics' law or principles then you  are able to understand physics's subject better. At the same time, it will be easier for u to remember them in a longer period.
Hopefully this post will help u to understand & memorize any physics definition in an effective manner. However for those who are weak in english, my only advice is ..rajin-rajinlah bukak dictionary :)

Spring Application

I'm almost sure that all of u had once ride this 'horse-ride' thing in a playground..If u are asked to design this spring that it can hold different weight of children and at the same time allow the kids to feel the bounce... what kind of spring features will u choose???

The features should be based on the following aspect ;

i. its spring constant value

ii. diameter

iii. coil thickness  

iv. type of metal

Give reason for each features that u've recommended.

U can give your version of answers in a comment section. Lets discuss it!!! 

"Gila Bola.. gila Fizik"

Hi guys...one week of school break had passed,hopefully u were enjoying it & at the same time did "plenty of revision" :)
Take this remaining week as an opportunity  to revise any form 4 topics that u r having problem with..and to those yang 'gila bola',actually u can revise lots of physics stufft while watching your favoriate team in the world cup..
Hmm..learning physics concept in world cup???? How???

Most footballer apply plenty of impulsive force concept ..While kicking a ball, they need to shorten the time of impact to produce bigger force.Thus they can kick the ball with powerful shots on goal..Even some boots are designed to give better impact during a shot on goal...just look at rooney's shot  :)

In another example,while  passing the ball they uses the inside of the foot and provides the largest surface area to contact the ball. This gives them a better control of where the ball should go.

Meanwhile the keeper should always increase the time of impact while catching the ball. By doing this the ball will exert minimise force, in the end he can catch the ball easily..Thats why a pair of glove is needed to suit this purpose.

Heading the ball also applies some physics concept. You can make full use of the ball's momentum. When your head collides with the ball, you share your momentum with it. The more momentum the ball gets from you, the faster and farther it will move. The bigger you are and the faster you're moving, the greater your momentum will be, and the more momentum you will have to share with the ball.
(recall principle of conservation of momentum)

"Bend it like Beckham"

A freekick taker should at least learn bernoulli principle..then he'll sure can bend the ball like beckham or christiano ronaldo :)
To bend it like beckham, you simply kick it slightly off center, causing it to spin horizontally.

• When the ball travels, air moves over the ball. The air will move more quickly around one side, making less pressure on that side of the ball (referring bernoulli..faster speed of air means lower pressure). 
• On the other side of the ball, the air moves more slowly, as the spin is going directly against the flow of the air, causing there to be more pressure on that side of the ball. 
• The ball is pushed in the direction from high pressure to low pressure, making the ball curve;The spinning ball produce different speed which produce difference in pressure.
•  Thus a resultant force is produced which causes the ball to be bent with a curvy motion. 

Do u get what i mean??...we can actually apply physics in almost everything we do in life. If u look at physics as a boring subject then u'll be easily getting bored..BUT if u look at it in a different perspective, trust me u'll find learning physics is loaded with lots of FUN :)

For this world cup...i definitely support Argentina or Spain..and i think England is dreaming to lift the trophy with that school boy goal keeping error. He  should take physics class and learn how to stop the ball effectively  :)

My last message for today will be...  "biar Gila BOla tapi celik FiZik"..adios

Physics gossip : 'Rotan vs Penampar'

Al kisah satu cerita...seorang pengawas pintar di salah sebuah sekolah asrama penuh bernama Shahir yang pernah dapat straight A dalam PMR  didenda kerana 'kantoi' mengedar & hisap rokok di kawasan sekolah..
Hari ini di depan perhimpunan, cikgu Mat a.k.a cikgu disiplin tercegat sambil merenung tajam si sharir yang tampak rileks ala-ala 'cool'.

Dengan garaunya cikgu Mat bersuara :OK murid2, inilah akibatnya kalau nak tunjuk 'terror' kat sekolah!!

Cikgu Mat : Shahir b Sabu..adakah anda mengaku bersalah??
Shahir        : Ya cikgu, saya bersalah. Saya hisap rokok sebab ia buat saya rasa 'cool'.

.....begitulah jawab shahir dgn selambanya..

Cikgu Mat : Oh, sebab awak mengaku salah, awak akan dihukum...Tetapi memandangkan awak seorang pelajar pintar ,jika awak boleh menjawab soalan daripada cikgu fizik ni dgn betul,  maka hukuman awak akan diringankan. Adakah awak nak cuba ??

Dgn muka yg selamba lagi tersengih si shahir menjawab:
 " Ok cikgu, saya confident boleh jawab..sebab saya  "cool" :)

Cikgu Mat : Baiklah, dengar soalan cikgu fizik ni baik-baik...
Shahir       :  'Ok cikgu..no hal'...

Cikgu fizik : Dengan menggunakan fizik konsep yang betul, antara 'kena penampar' dan kena 'rotan'..manakah yang lebih sakit jika daya hayunan yang dikenakan adalah sama??? Terangkan kenapa ??

..Shahir terus tersenyum :) bila mendengar soalan tersebut..lalu menjawab seperti berikut..

Shahir       : Mestilah kena rotan lagi sakit.

Cikgu Mat : OK!, kenapa???

Shahir       : Kalau kita tengok, rotan tu batangya halus. Luas permukaan atau 'area'nya kecil. Kita ambil konsep 'pressure', iaitu  Pressure = Force / Area...memandang kan ''pressure' berkadar songsang dengan 'area'..Jadi kalau 'area' kecil,  tekanan yang akan dikenakan akan bertambah. Kalau kena tampar tak sakit sangat kerana luas pemukaan tangan manusia lebih besar dari rotan ni. Sebab tu lah kena rotan akan rasa lebih sakit :)

Cikgu Mat : macam mana cikgu??..boleh terima ke


Cikgu Fizik: Hmm.. jawapan dia boleh diterima.

Shahir : heheh..kan saya dah cakap tadi, saya ni memang "Coo...."
(belum sempat shahir habis cakap, satu bunyi kuat melekap ke pipinya. PANGGGGG!!!!!)
Habis merah padam muka si Shahir)

Cikgu Mat: Disebab awak jawab dengan betul.. hukuman awak telah diringankan, maka awak hanya kena penampar..andai kata kalau awak jawab salah, sudah pasti awak kena rotan.

lalu dengan selambanya cikgu fizik pula bertanya...
"Amacam!...lepas kena penampar ada rasa "COOL" ke "HOT"????  Kalau "COOL" jugak maknanya kulit awak memang tebal seolah-olah mcm ada 'high specific heat capacity' :)

So moral of the story..kalau pun kita pandai kat sekolah, cubalah belajar hormat guru dan patuhilah peraturan yang telah ditetapkan. Tak guna kalau pandai, tapi berlagak sombong. Lagi satu, merokok takkan menjamin yang kita akan menjadi lebih 'cool' walaupun kita seorang genius,...renung-renungkan lah!!


Nukilan 'original' cikgufizik@ www.physics4spm.com