## Wednesday, December 22, 2010

### Reflection of waves

Reflection of a wave occurs when a wave strikes an obstacle. The wave undergoes a change in direction of propagation when it is reflected. The phenomenon of reflection of waves obeys the Law of reflection where:
1. The angle of reflection is notequal to the angle of incidence.
2. The incident wave, the reflected wave and normal lie in the same plane which is perpendicular to the reflecting surface at the point of incidence.

Characteristics of reflection of waves:
1. The wavelength , speed and frequency of the reflected waves is the same as that of the incidence.
2. Angle of incidence = angle of reflection.
3. Direction of propagation of wave changes. Application of reflection of waves:

2. Makeup mirror
3. Car rear mirror and side mirror for your safety .
4. Optical fibre
5. Ultrasonic
6. Fishing with sonar.
7. Seawall to deflected the energy of the waves from the coast. Seawall

Fishing with sonar

## Monday, December 20, 2010

### Displacement- Time graph and displacement -Distance Graph for a wave The sinusoidal graph shown is a graph of displacement, s against time , t of a load on a spring.

O is called the equilibrium position.

From a displacement-time graph for a wave, we can obtain
i) amplitude, a ,and
ii) period, T. From a displacement- distance graph for a wave, we can obtain
i) amplitude, a ,and
ii) wavelength, λ

Relationship between Speed, (v) Wavelength,(λ) and Frequency (f)

The speed of a wave is determined by its wavelength, λ, and its frequency, f , according ti the equation V= f λ

For a wave moving at constant speed, increasing the frequency will result in a decrease in the wavelength.

For a wave moving at constant speed, decreasing the frequency will result in an increase in the wavelength.

Work example:

What is the frequency of water waves with the wavelength of 3.0 cm and traveling at a speed of 1.5 cm/s ?

solution :

Step 1: write formula first
V= f λ

step 2 : Substitute all given info into formula
1.5
cm/s = f x 3.0 cm

Step 3:find unknown
f = 0.5 Hz

## Wednesday, December 8, 2010

### Wave Properties

In merupakan bab pertama dalam syllabus tingkatan 5. Murid 5 UM dan 5UKM anda diminta membuat kuiz yang disediakan. Sebarang pertanyaan boleh ditulis pada Cbox atau hantar ke Facebook saya.

1. Waves are produced by vibrating systems. Vibrating systems

2. Waves transfer energy. Waves that travel through a medium transfer energy without transferring matter. 3. In transverse waves, the direction of waves propagation is perpendicular to the direction of vibration of the particles.
Example: water waves, light waves and electromagnetic waves. 4. In longitudinal waves, the direction of wave propagation is parallel to the direction of vibration of the particles.
Longitudinal waves need a medium to propagate. This type of waves cannot propagate through a vacuum.
Example: a sound wave. 5. A wavefront is an imaginary line representing all parts of a wave in which particles are vibrating in the same phase and have the same distance from the source.
The direction of propagation of waves is always perpendicular to the wavefront. 6. Amplitude, a, is the maximum displacement from the equilibrium position.

7. Period, T, is the time required to make one complete oscillation.

8. Frequency, f, is the number of complete oscillations made in one second.

9. Wavelength, is defined as the distance between two consecutive points that are in phase. ( i ) For a transverse wave, wavelength can be measured as the distance from one crest and also the distance from one trough to the next trough. (ii ) For a longitudinal wave, wavelength can be measured as the distance between
two consecutive compressions or two consecutive rarefactions. ## Friday, December 3, 2010

### Gred SPM mulai 2009

Berikut merupakan gred SPM yang mula diperkenalkan mulai 2009. SPM Candidates All the Best!

## Monday, November 29, 2010

### SPM tips ~ paper 2 ( light )

Diagram 9.1 and Diagram 9.2 show light rays from two identical objects passing through two identical convex lenses. Both lenses produce real images. F is the focal point for the lens.
Rajah 9.1 dan Rajah 9.2 menunjukkan sinar cahaya dari dua objek yang serupa melalui dua kanta yang serupa. Kedua-dua kanta tersebut menghasilkan imej nyata. F adalah titik fokus untuk kanta tersebut. (a)
(i)
Name the phenomenon involved. [1 mark]
Namakan fenomena yang terlibat. [1 markah]

Hits for solving the problem :
Refraction of light is the bending of light ray at the boundary as it travels from one medium to another.
Reflection of light occurs when the light ray strike the surface of mirror.

ii)
Observe Diagram 9.1 and Diagram 9.2. Compare the object distance, the image distance, the size of the image and the power of the lens. Relate the size of the image with the object distance. [5 marks]

Perhatikan Rajah 9.1 dan Rajah 9.2. Bandingkan jarak objek, jarak imej, saiz imej dan kuasa kanta. Hubungkaitkan saiz imej dengan jarak objek. [5 markah]

Hits for solving the problem :
• Pay attention to the marks allocated. the marks usually indicates the number of points required.
• Understand the task
1. Compare the object distance,
2. Compare the image distance,
3. Compare the size of the image
4. Compare the power of the lens.
5. Relate the size of the image with the object distance.

(b)
Diagram 9.3 shows the structure of a simple camera.
Rajah 9.3 menunjukkan struktur sebuah kamera ringkas. (i)
Explain how the camera is able to capture the image of a distant object. [3 marks]
Terangkan bagaimana kamera boleh merakam imej suatu objek jauh. [3 markah]

Hits for solving the problem :
• Pay attention to the marks allocated , the marks usually indicates the number of points required

(ii)
State the range of the object distance where the image formed is sharp. [1 mark]
Nyatakan julat jarak objek bagi kedudukan imej yang tajam. [1markah]

(c)
A student is given two convex lenses, R and S. The focal length for R and S are 20 cm and 5 cm respectively. Suggest and explain how to build a microscope which produces a sharp and magnified image based on the following aspects:

Seorang pelajar diberi dua kanta cembung R dan S. Panjang fokus untuk R dan S adalah 20 cm dan 5 cm masing-masing. Cadang dan terangkan bagaimana anda membina sebuah mikroskop yang menghasilkan imej yang tajam dan dibesarkan berdasarkan aspek-aspek berikut:

Hits for solving the problem :
Underline the important information given in the question, such as focal length for each lens, build a microscope...

(i)
Arrangement of lenses
Susunan kanta

(ii)
Position of object
Kedudukan objek

(iii)
Position of the first image
Kedudukan imej pertama

(iv)
Distance between the two lenses
Jarak antara kedua-dua kanta

(d)
Suggest two modifications that need to be done to the microscope to produce a bigger final image. [2 marks]

Cadangkan dua ubahsuaian yang perlu dibuat pada mikroskop untuk menghasilkan imej akhir yang besar .[2 markah]

Hits for solving the problem :
M= Mo x Me

## Sunday, November 28, 2010

### SPM Trial MARA 2010 ~ paper 2 ( waves ) Diagram 8.1 shows Aini trying to open the house’s front gate using a remote control. Even though Amin is blocking her, the gate can still be opened.
Rajah 8.1 menunjukkan Aini cuba membuka pintu pagar rumah dengan menggunakan alat kawalan jauh. Walaupun Amin menghalangnya pintu pagar masih boleh dibuka.
(a)
(i)
Name the wave phenomenon involved
Namakan fenomena gelombang yang terlibat.

ii)
On Diagram 8.2, draw the wave pattern based on the situation in Diagram 8.1. (b)
Table 8.1 shows the characteristics of three waves, X, Y and Z to be used in the remote control for the gate. Calculate the wavelength of each wave.
Jadual 8.1 menunjukkan ciri-ciri untuk tiga gelombang, X, Y dan Z yang akan digunakan dalam alat kawalan jauh bagi pintu pagar. Hitungkan panjang gelombang bagi setiap gelombang. (i)
Wave X
Gelombang X

(ii)
Wave Y
Gelombang Y

(iii)
Wave Z
Gelombang Z

(c)
(i)
Based on your answers in 8(b), which wave is the most suitable to be used in the remote control for the gate?
Berdasarkan jawapan anda di 8(b), gelombang manakah yang paling sesuai digunakan untuk alat kawalan jauh bagi pintu pagar itu?

(ii)
State one reason for the answer in 8(c)(i).
Nyatakan satu sebab bagi jawapan 8(c)(i).

(d)
Based on the values of the wave speed shown in Table 8.1,
Berdasarkan nilai laju gelombang dalam udara yang ditunjukkan dalam Jadual 8.1,

(i)
Predict what wave X is.
Ramalkan gelombang X.

(ii)
State one application for wave X.
Nyatakan satu kegunaan gelombang X.

a)
i)
Diffraction of waves
ii) b)

i) Velocity = Frequency × Wavelength
3.3 x 10 2 = 4. 0 x 105 x wavelength
wavelength = 8.25 x 10
-3 m

ii) wavelength = 0.75m

iii) wavelength = 7.5 x 1o -11

c)
i) wave Y

ii) The e of effect diffraction is very obvious.

d)

i) Sound wave

ii)Disintegration of kidney stones // Locating an object under water // remove plaque from teeth

## Saturday, November 27, 2010

### SPM Trial MARA 2010 ~ paper 2 ( Resistance ) Diagram 6.1 and Diagram 6.2 show two electric circuits each consisting of a copper wire.
Rajah 6.1 dan Rajah 6.2 menunjukkan dua litar elektrik masing-masing mengandungi seutas wayar kuprum.

(a)
Name the quantity measured by the ammeter.
Namakan kuantiti yang diukur oleh ammeter.

Hits for answer the problem :
Key words " quantity"

(b)
(i) Compare the thickness of the copper wire in Diagram 6.1 and Diagram 6.2.
Bandingkan ketebalan wayar kuprum dalam Rajah 6.1 dan Rajah 6.2.
(ii)
Compare the ammeter reading in Diagram 6.1 and Diagram 6.2.
Bandingkan bacaan ammeter dalam Rajah 6.1 dan Rajah 6.2.

(iii) Relate the thickness of the copper wire to the ammeter reading.
Hubungkaitkan ketebalan wayar kuprum dengan bacaan ammeter .

(iv)
Relate the thickness of the copper wire to its resistance.
Hubungkaitkan ketebalan wayar kuprum dengan rintangan. (c)
You are provided with three light bulbs labelled A, B and C labelled A, B and C as shown in
Diagram 6.3.
Anda dibekalkan dengan tiga mentol Anda dibekalkan dengan tiga mentol berlabel A, B dan C seperti dalam Rajah 6.3. seperti dalam Rajah 6.3. Draw and label an electric circuit connecting all the three bulbs in which all the bulbs should light up with normal brightness connected to a power supply of 240 V alternating current . Add switches to the circuit.
Lukis dan label satu litar elektrik yang menyambungkan ketiga-tiga mentol di mana semua a mentol seharusnya menyala dengan kecerahan normal apabila disambungkan kepada bekalan kuasa 240 V arus ulang-alik. Tambahkan suis pada litar anda.

a) Electric current

b)
i) Thickenss of the copper wire of diagram 6.2 thicker than diagram 6.1.

ii) Ammeter reading in diagram 6.1 is less than diagram 6.2.

iii) The thicker the copper wire, the higher the ammeter reading.

iv) The thicker the copper wire, the lower the resistance.

c) ## Friday, November 26, 2010

### SPM Trial MARA 2010 ~ paper 2 ( Thermal Equilibrium )

Question 5

A student carries out an activity to record the temperature change of oil and water. Both liquids are heated by identical heaters for two minutes. The initial temperature of oil and water are 30oC.
Seorang pelajar membuat aktiviti untuk merekod perubahan suhu minyak dan air. Kedua cecair dipanaskan oleh pemanas yang serupa selama dua minit. Suhu awal minyak dan air adalah 30oC. (a) Name the condition in which the temperature of the water is equal to the temperature of the thermometer.
Namakan keadaan di mana suhu air adalah sama dengan suhu termometer.

Hits for answer the problem :
Key words " temperature of the water is equal to the temperature of the thermometer.
"

(b)
Observe Diagram 5.1 and Diagram 5.2. Compare,
Perhatikan Rajah 5।. dan Rajah(b) 5 .2. Bandingkan

(i) the mass of oil and mass of water.
jisim minyak dan jisim air.

Hits for answer the problem :
Observe the compression balance indicator //scale.

(ii) the temperature change in oil and also in water.
perubahan suhu minyak dan suhu air.

Hits for answer the problem :
Observe the thermometer .

(c)
(i) Compare the amount of heat supplied by the heater to the oil and to the water.
Bandingkan jumlah haba yang dibekalkan oleh pemanas kepada minyak dan kepada air.

Hits for answer the problem :
key words "Both liquids are heated by identical heaters for two minutes"

(ii) Compare the amount of heat absorbed by oil and water.
Bandingkan jumlah tenaga yang diserap oleh minyak dan air.

Hits for answer the problem :
Assuming that no heat lost to the surroundings,
heat received by liquids = heat given out by the heater.

Q=mcӨ = Pt

(iii) Name the physical quantity that will explain the comparison you made in 5(b)(ii).
Namakan kuantiti fizik yang menerangkan perbandingan yang dibuat dalam 5(b)(ii).

(d)
If the heating time is increased to 5 minutes, will there be any change in the physical quantity in (c)(iii)? Explain your answer.
Jika tempoh pemanasan ditambah kepada 5 minit, adakah sebarang perubahan pada kuantiti fizikal pada (c)(iii)? Terangkan jawapan anda

a) Thermal Equilibrium

b)
i)Mass of the oil and water are same .
ii)Temperature of oil is higher than temperature of water

c)
i) Heat supplied by the heater to the oil is equal to heat supplied to the water
ii) The amount of heat absorbed by oil and water are same .
iii) Specific heat capacity

d)
When two objects of equal masses are heated at equal rates, the object with the smaller heat capacity will have a faster temperature increase.

The specific heat capacity of oil is smaller than water, therefore oil show higher temperature.

## Wednesday, November 17, 2010

### SPM Trial MARA 2010 ~ paper 2 ( Impulsive force )

Question 2 Diagram 2 shows a baseball player wearing a soft thick glove to catch a ball during a baseball match.
Rajah 2 menunjukkan seorang pemain bola lisut memakai sarung tangan tebal yang lembut untuk menangkap bola semasa pertndingan bola lisut.

(a) What is meant by impulsive force?
Apakah maksud daya impuls?

(b) The ball of mass 0.15 kg moves with a velocity of 20 m s when it is hit.
Calculate the impulsive force acting on the glove when the time of impact is 8.0 x 10 -2 s.

Bola berjisim 0.15 kg bergerak dengan kelajuan 20 m s apabila dipukul.
Hitungkan daya impuls yang bertindak ke atas sarung tangan jika masa tindakbalas 8.0 x 10 -2 s.

(c) Compare the impulsive force if the baseball player wears a hard glove to catch the ball. Explain your answer.
Bandingkan daya impuls yang di hasilkan jika pemain itu menggunakan sarung tangan yang keras untuk menangkap bola. Jelaskan jawapan anda.

Hits for answer the problem :
Decreasing the time of impact will increase the magnitude of the impulsive force, and vice versa.

a)
Impulsive force is defined as the rate of change of momentum in a collision or explosion.

b) c) A larger impulsive force is produced if the baseball player wears a hard glove. Because the time interval of interaction is small.

## Tuesday, November 16, 2010

### SPM Trial MARA 2010 ~ paper 2 ( Water tank ) Question 7

Diagram 7 shows a public water tank which supplies water for domestic use to a residential area.
Rajah 7 menunjukkan sebuah tangki air awam yang membekalkan air untuk kegunaan domestik di satu kawasan perumahan.

(a)
State one factor which affects pressure in a liquid.
Nyatakan satu faktor yang mempengaruhi tekanan dalam cecair.
Hits for solving problem :
Liquid pressure increase with depth//height, and increase with density.
(b)
Based on Diagram 7, calculate the water pressure at X.
(Density of water = 103 kg m-3).
Berdasarkan Rajah 7, hitungkan tekanan air di X.
( Ketumpatan air =103 kg m-3).
Hits for solving the problem:
~ list all info given or underline the importance information given.
Given ρ, g ,h and find P .
~ state the formula, P = ρ g h
~ substitute the value for each quantity
~ answer with the correct unit.

(c)
Tenants on the fifth floor of the apartment block are unable to obtain tap
water. Why?
Penghuni di tingkat lima blok pangsapuri tidak menerima bekalan air paip. Mengapa?

(d)
Suggest and explain modifications to the water distribution system shown in Diagram 7, to ensure the following :
Tangki air itu tidak dapat memenuhi keperluan semua penghuni di blok pangsapuri lima tingkat. Cadang dan terangkan pengubahsuaian yang perlu dilakukan untuk setiap yang berikut:

(i)
Sufficient water supply for all area residents.
Bekalan air yang mencukupi untuk semua penghuni kawasan.

(ii)
Water supply reaches the fifth floor of the apartment building.
Bekalan air boleh sampai ke tingkat lima blok pangsapuri.

e)
The public water supply system often faces a problem in delivering water to water tanks located on tall buildings.
Suggest and explain one other way to overcome this problem.
Sistem bekalan air awam kerapkali menghadapi masalah untuk menyalurkan air ke tangki
air yang berada di bahagian atas bangunan tinggi.
Cadangkan dan jelaskan satu cara lain untuk mengatasi masalah ini.
Hits for solving problem (c) - (e):
In prublic water supply system, the water is pumped up to a water tank located higher than the building in that area.
Due to the gravitational pull, water in the storage tank is maintaned at a high pressure and enables water to flow to the lower area ( consumers )

a) The height of water tank.
b)
P = ρ g h
= 1000 x 10 x 10
= 100 000 N/ m
= 100 000 Pa

c)
Water tanks are tall to provide pressure.
The location of fifth floor apartment is exceed the height that the tank's water pressure can handle.

d)
i) Build a larger water tank,to holds enough water for all area residents.
ii) Ensure water tank located higher than apartment , to provide the necessary pressure.

e) Install a pump to provide pressure.

## Monday, November 15, 2010

### SPM Trial MARA 2010 ~ paper 2 ( CRO )

Question 4

A cathode ray oscilloscope ( C. R. O) is an instrument that converts electronic and electric signals to a visual display.

Diagram 4.1 shows the structure of a simple cathode ray oscilloscope (CRO).
Rajah 4.1 menunjukkan struktur satu osiloskop sinar katod ringkas (OSK) . (a) (i) Based on Diagram 4.1, name the component T.
Berdasarkan Rajah 4.1, namakan komponen T.

Hints for solving the problem (ii) and (iii) :
The process of emission of electrons from the surface of a heated metal is known as thermionic emission.

This is because some of the electrons have gained enough kinetic energy to break free from the metal surface and escape to the surroundings.

(ii) Explain what happens to the electrons on the surface of T when T is heated.

Terangkan apa yang berlaku kepada elektron pada permukaan T jika T dipanaskan.

(iii) Name the physics process in (a)(ii).
Namakan proses fizik yang berlaku dalam (a)(ii).

(b) A student uses a CRO to study the output voltage of a bicycle dynamo. The time-base is set at 100 ms/division and the Y gain control is set at 0.5 V/division.

Seorang pelajar menggunakan OSK untuk mengkaji voltan output yang dijana oleh sebuah dinamo basikal. Dasar masa telah dilaraskan pada 100 ms/bahagian dan gandaan Y dilaraskan pada 0.5 V /bahagian. Hits for solving the problem: (i) Calculate the frequency of the wave produced by the bicycle dynamo.
Hitungkan frekuensi gelombang yang dihasilkan oleh dinamo basikal.

Hits for solving the problem:
f = 1/ T

(ii) On Diagram 4.2, draw a new trace to show the voltage output if the frequency of the dynamo is doubled.

Pada Rajah 4.2, lukiskan surihan yang baru untuk menunjukkan voltan output jika frekuensi dinamo digandakan.

a)

(i) Cathode

(ii)Cathode or T emits electrons when it is heated.

(iii) Thermionic emission

b)

(i) time taken to complete one oscillation , T = 4 x 100 ms

T= 400 ms

Frequency , f = 1 / T

f = 1/ 400 ms

f = 2.5 Hz

(ii) ## Sunday, November 14, 2010

### Tips for Physics Paper 1 and paper 2

Paper 1

1. Cancel or mark (x) which is wrong option then choose.

2. Always refer the formula given on formula list.

( one step calculation only because 1 question = 1 mark)

3. Blacken each finished answer immediately.

Paper 2

1. Definition of the term in Physics. ( please refer to text book)

Force, work, power, momentum, inertia, impulsive force, coherent, pressure, temperature and heat...

2. The principle in Physics and application.

Force in equilibrium, thermal equilibrium, Pascal's principle, conservation of momentum.

3. The Law in Physics and application.

Hooke's Law, Ohm's Law, Charles Law, Boyle's Law, Newton"t first law, Newton Second Law...

4. Drawing skills ( Use pencil, ruler and other suitable drawing tools)

Total internal reflection, ray diagram, interference , field circuit, refraction of wave, circuit...

5. Graph skills

Axis, plotting, scale, straight or curve line, gradient , extrapolation.

## Thursday, November 11, 2010

### Decision Making - - Hydraulic jack

Diagram shows a hydraulic jack in a car service centre. Table below shows four type of hydraulic oil, K, L, M and N , with different specifications. You are required to determine the most suitable hydraulic oil to run the hydraulic jack. Study the specifications of all four types of hydraulic oil from the following aspects:

i ) Boiling point of the hydraulic oil

ii) Specific heat capacity of the hydraulic oil

iii) Density of hydraulic oil

iv) Rate of vaporisation of hydraulic oil

i) Has high boiling point
~ so that hydraulic fluid not easily boiling

ii) Has higher specific heat capacity
~ so that it can't be easily became hot

iii) Has lower density
~ so the hydraulic oil is not heavy

iv) Has lower rate of vaporisation
~ Volume of the hydraulic oil not easily vaporise.

Hydraulic oil L is chosen

Reason :
L has high boiling point, higher specific heat capacity, lower density and lower rate of vaporisation .

## Tuesday, November 9, 2010

### Structure question -( concave mirror)

Percubaan SPM MRSM 2010

Diagram 1 shows an object placed in front of a mirror.
Rajah 1 menunjukkan satu objek diletakkan di hadapan sebuah cermin. (a) Name the type of mirror shown in Diagram 1.
Namakan jenis kanta yang digunakan dalam Rajah 1.

Hints for solving the problem :
A convex mirror curves outwards.
A concave mirror curves inwards.
(b) Draw the image in the box given in Diagram 1.
Lukiskan imej dalam petak yang disediakan pada Rajah 1.

Hints for solving the problem :
Draw the image with its tail on the axis. The head is where the two reflected rays meet.
convex mirror typically make a virtual image.
A virtual image is shown using a dotted line.

(c) Based on Diagram 1, tick the correct statement about the image formed.
Berdasarkan Rajah 1. tandakan pada pernyataan yang betul mengenai imej yang terbentuk.

[] The image can be formed on a screen.
[] Imej boleh terbentuk pada skrin.
[] The image cannot be formed on a screen.
[] Imej tidak boleh terbentuk pada skrin.

Hints for solving the problem :
Real image can be displaced on a screen.
Virtual image can be seen by the observer but not be displaced on a screen.

(d) What happens to the size of the image if the object is placed at X?
Apakah yang terjadi pada saiz imej jika objek diletakkan pula di X ?
Hints for solving the problem :
The image appears larges in size when the object is nearer to the convex mirror.

(a) Convex mirror
(b) (c)The image cannot be formed on a screen.
(d) Image is smaller than original size

## Thursday, October 28, 2010

### Tip- SPM Fizik kertas 3

A student investigate how the extension of a spring changes with the load acting on a spring.
Diagram 1.1 and 1.2 show what happens when two different loads are hang on two identical springs. Based on the information and the observation above:
Berdasarkan maklumat dan pemerhatian di atas:

a) State one suitable inference that can be made
Nyatakan satu inferens yang sesuai [1 mark]

* pesanan :
baca soalan dengan teliti dan carikan pembolehubah yang tersurat dalam maklumat yang diberi.
Contohnya pemboleh ubah boleh laras ( manipulated variable ) ialah beban load // force // mass) yang digunakan , dan pemboleh ubah bersandar ( responding variable) ialah pemanjangan spring. ( extention of spring ).

Sambungkan pemboleh ubah yang dikesan dengan kata kunci seperti
i) MV influences RV
ii) RV is influenced by MV
iii) RV depends on MV.

b) State one appropriate hypothesis for an investigation
Nyatakan satu hipotesis yang sesuai dikaji [1 mark]

* pesanan :
Tuliskan hubungan MV dengan RV .

c) With the use of apparatus such as a spring, slotted weights and other apparatus, describe an experimental framework to test your hypothesis stated in 2(b)
In your description, state clearly the following:

Menggunakan alat radas seperti spring, jisim berslot dan lain-lain radas yang sesuai, terangkan suatu rangka kerja eksperimen untuk menguji hipotesis anda di 3(b).
Dalam penerangan anda, jelaskan perkara-perkara berikut

(i) The aim of the experiment
Tujuan eksperimen

* pesanan :
Gunakan kata kunci
i) to study...
ii) to investigate...

(ii) The variables in the experiment
Pembolehubah didalam eksperimen

* pesanan :
senaraikan ketiga-tiga pemboleh ubah.

(iii) The list of apparatus and materials
Senarai radas dan bahan

* pesanan :
Alatan yang dicadangkan perlu disaling semula, dan pastikan alatan yang disenaraikan boleh digunakan untuk menguju MV dan RV yang anda cadangkan.
Contoh:
Pembaris (Meter rule ) --> mengukur panjang spring.

(iv) The arrangement of the apparatus

* pesanan :
Lukiskan dan labelkan susunan radas yang berfungsi.

(v) The procedure of the experiment which include the method of controlling the manipulated variable and the method of measuring the responding variable.
Prosedur eksperimen termasuk kaedah mengawal pembolehubah dimanipulasi dan kaedah mengukur pembolehubah bergerakbalas

* pesanan :
Senaraikan arahan menguju MV dan RV, dicadangkan arahan mengulangi ujikaji sebanyak 4 kali .

(vi) The way you would tabulate the data
Cara untuk menjadualkan data

* pesanan :
Lakarkan jadual berlabel dan tandakan unit kuantiti fizikal.

(vii) The way you would analyse the data
Cara untuk menganalisis data [10 marks]

*pesanan:

Lakarkan graf dengan tandakan MV (di paksi-x) dan RV ( dipaksi-y) pastikan unit yang betul diberi.

a) Inference :
The pulling force influences the extension of the spring//
The length of spring is influenced by the pulling force//
Length of spring depends on the force acting on it.

b) Hypothesis:
The bigger the force , the longer the spring.//
When the force(mass) increases, the length of the spring increase

C)
i) Aim:
To investigate the relationship between force //mass and the extension of the spring

ii)
Manipulated variable : Force, F// mass
Responding variable: Extension of spring, x
Fixed variable: Diameter// stiffness of spring/ the initial length, lo/ spring constant of spring,k

iii) List of apparatus/ materials :
Spring, pin, slotted weight, retort stand with clamp, meter rule and plasticine.

iv) Arrangement of the apparatus( with labels ) v)
~ Method of controlling the manipulated variable :
1. Determine the initial length, lo, without any slotted weight hung to the spring.
2. Hang a slotted weight of mass 50 g, (force/weight of 0.5 N) and measure the length of the spring .

~Method of measuring the responding variable :
3. Calculate the extension of the spring, x using the formula ( length l) – (initial length, lo)

~Repeating :
4. Repeat the experiment using mass of 100g, 150g, 200g and 250g (or force, F= 1.0 N, 1,5 N, 2.0 N and 2,5 N)

vi) Selamat Maju Jaya.

## Monday, October 25, 2010

### SPM Trial MARA 2010 ~ paper 2 ( Radioactivity )

Question 3 Diagram 3 shows a Geiger-Muller tube (GM tube) and a rate meter which are used to detect the level of milk in containers in a factory.
Table 3 shows the readings recorded by the rate meter for four containers P, Q, R and S when a radioactive source is placed near the containers. The rate meter records a reading of 100 counts per minute when there is no radioactive source nearby.

Rajah 3 menunjukkan sebuah tiub GM dan alat meter kadar digunakan untuk mengesan paras susu di dalam bekas di sebuah kilang.
Jadual 3 menunjukkan bacaan meter kadar bagi empat bekas P, Q, R dan S bila suatu sumber radioaktif diletakkan berhampiran bekas. Meter kadar mencatatkan bacaan 100 bilangan per minit jika tiada sumber radioaktif diletakkan berdekatan. (a)
Name the radiation emitted by the radioactive source.
Namakan sinar radiasi yang dikeluarkan oleh sumber radioaktif itu.

Hints for solving the problem :
Beta or gamma source are used, depending on the thickness and the density of the material to be measured.

(b)
(i)
Based on Table 3, which container has the least amount of milk?
Berdasarkan Jadual 3, bekas yang manakah mempunyai kuantiti susu paling kecil?
Beri satu sebab bagi jawapan anda.

Hints for solving the problem :
The reading depends on the milk quantity in the container and it gets higher as the milk is under level.

(ii)
State the actual rate meter reading for Q.
Nyatakan kadar bacaan sebenar bagi Q

Hints for solving the problem :
When there is no radioactive source nearby the detector detect natural background radiation . (cosmic radiation, solar radiation, etc)

(c) The mass of a radioactive source is reduced from 80.0 g to 20.0 g in 30
seconds. Calculate its half-life.

Jisim suatu sumber radioaktif menyusut dari 80.0 g kepada 20.0 g dalam masa 30 saat.
Hitungkan setengah hayat bagi bahan radioaktif tersebut.

Hints for solving the problem :
The half-life of a radioisotope is the average time it takes for half of the remaining radiative atoms to decay to a different atom.

a) beta because it can penetrate box and liquid and is less
dangerous than gamma.
b)
(i) R has the least a mount of milk. highest mean it allow more beta to passes though.
(ii) 566 - 100 = 466 counts per second
c) 80 --> 40 --> 20
it undergo 2 half-life.
half life = 30/ 2 = 15 secs

## Friday, October 22, 2010

### Trial Selangor 2010 ~ paper 2 ( transformer )

Question 10 :( Selangor trial 2010) Diagram 10.3 shows a simple step-up transformer.
Rajah 10.3 menunjukkan sebuah transformer injak naik yang ringkas.

i) Explain why step-up transformers are used in the transmission of electricity.
Terangkan mengapa transformer injak naik digunakan dalam penghantaran elektrik.

Notes :
A transformer changes the magnitude of an alternating current voltage. ( Direct current is not transformed, ad dc does not vary its magnetic fields)
A step-up transformer supplied an output voltage that higher that the input voltage.

* Penting transformer hanya meningkatkan voltan elektrik sahaja. Elakkan tulis arus elektrik ( Current).

(ii) You are required to modify the transformer in Diagram 10.3 so that it can be used as a laptop adapter with high efficiency and output of 20 V direct current.
Your suggestions and explanation should be based on the following aspects:

Anda dikehendaki mengubahsuai transformer pada Rajah 10.3 supaya ia boleh digunakan sebagai adapter komputer riba yang berkecekapan tinggi dengan mengeluarkan output arus terus 20 V.
Cadangan dan penjelasan anda haruslah berdasarkan aspek-aspek berikut:

a.
Type of the core used.
Jenis teras yang digunakan.

Note:
The alternating current flowing through the transformer continually magnetises and demagnetises the core. work has to be done to change the magnetic field in core which contributes to energy loss.
Use cores made from soft-iron can be easily easily magnetised and demagnagtised.

Materials and diameter of the wire used.
Bahan-bahan dan diameter dawai yang digunakan.

Note:
All wires will have resistance, heat is produced when current flow through them.r
The resistance will reduce as the wire is thicker. ( bigger diameter )

c.
Ratio of the number of tums in the primary coil to the secondary coil.
Nisbah bilangan lilitan gegelung primer kepada gegelung sekunder.

Note:
Ratio of the number of tums in the primary coil to the secondary coil is called turns ratio ( also known as voltage ratio)
* write the primary turns no. first.
Example => 1 to 20 is step-up transformer, whereas a 20 to 1 would be a step-down transformer.

d.
The arrangement of the primary coil and the secondary coil.
Susunan gegelung primer dan gegelung sekunder.

Note:
Electrical energy is lost when a fraction of the magnetic field produced by the primary coil does not link with the secondary coil.

e.
The number of diodes used.
Bilangan diod yang digunakan.

Note:
Two full-wave rectification methods. Bridge rectifier--> four diode are used
and center tap rectifier --> two diode are used

i) The greater the transmission voltage, the smaller the current in the
power lines.
ii) Power loss during transmission due to resistance will be smaller.

a.
-
laminated soft iron core
~ easily magnetised or
demagnetised
~ to reduce the effect of eddy
current .

b.
-copper wire & large diameter
~
reduce heat loss due to
resistance

c.
Np : Ns
240 : 20
24 : 2
12 : 1
~ to reduce output voltage

d.
-Wind the secondary coil on
top of the primary coil
~ to reduce the leakage of
magnetic flux

e.
- 2 or 4 diodes
~to produce full-wave
rectification