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Search Physics SPM:
Current & Voltage Relationship
In this section 2.2:
U must be able to analyse the relation between current & Potential difference or sometimes known as voltage. By understanding the concept, we then can deduce a law called Ohm's law. The experiment that derives ohm's law is so important..please study& understand it properly..it quite famous in exam.,.
Here i give u list of important things that might be asked in exam
1. Define potential difference??
refer to your text/ reference book..then try to watch this
So basically,voltage is a work done per unit charge.
2.U must also be able to Plan & conduct an experiment to find the relationship between current & potential difference(voltage).
I want to remind u again, please make sure you know how to design this experiment.
3.Next, u must know
What is the relationship between current & potential diffrence (voltage)??
Voltage(V) is directly proportional with current (I). So if current(I) increases, voltage(V) also increases.
4. Then.. a must for u to know how to...
..State OHm's Law:
Current flowing through a conductor is directly proportional to potential diffrence at constant temperature.
Ohmic conductor obeys ohms law, i.e the graph of V vs I will be a staight line.
Non ohmic conductor wont give a straight line graph.
5. After that..u must be able to define RESISTANCE.
Resistance = ratio of voltage over current
i.e by formula R= V/I. the unit is ohm or Ω.
Watch this video to get a clear picture about all the relationship between V,I & R ...
Ohms Law
SPM 2009 : Welcome to Electricity
Dear all..now I’ll be discussing the next chapter Eleccity. B4 I go further, please bear in mind, in form 5, 3 out of the 5 topics comes from a word ElecTRO (electricity,electromagnet, electronics)
Electricity is the fundamentals..u really need to understand tis chapter coz its basic shall be applied in next 2 chapters..lets go deeper
2.1 Analysing Electric fields & Charge flow..
In this subtopic u must be able to:
1. Relate between electron (charge) flow & current:
So what does it mean by electrical charges?
In electrical current, the electrical charges are flowing electrons (-ve charged).
Thus the relationship is ..:If electrons are flowing, current will be flowing as well!
(Note:Check your reference book..refer details on Van Der Graff)
2. The next outcome..u must know how to define Current.
What is current?
Current is the rate of flow of charge
By formula: I = Q/t
I = current , unit is ampere(A)
Q =charge, unit is coulomb (C )
t = time taken (s)
3. Describe an electric field??
- an electric field is a region in which an electric charge experiences a force.
- lines of electric field moves away from + ve charge
- lines of electric field points towards - ve charge.
5. U also need to describe the effect of electric field :
Watch these video..then refer yr reference book..or text book(pg46)
effect on pingpong ball
effect on candle flame
SPM 2009 Notes : Chapter 1 - Wave
Basically i've finished discuss SPM-Wave in my blog. However not everything have been covered. For this reason i attached a reliable notes for your referenceo..hopefully u don't have to buy another reference book :)
It might takes some time to load..be patient k.
Electromagnetic Waves Q & A
Q1: SPM2003/P1
click to enlarge
in this kind of question u 've no choice..u need to memorize the spectrum.
Q2 : SPM2003/P1
At an airport, a passenger’s bag is placed in the baggage scanner.
A X-ray
B gamma rays
C ultraviolet rays
U infrared rays
Recall back:
Electromagnetic waves
SPM: Electromagnetic Waves
Now lets go in depth about electromagnetic waves...
1. What is electromagenetic waves??
A wave that consist of a combination of oscillating electric & magnetic fields pependicular to each other.
Watch this!
2. ..its properties???
- a transverse wave
- carries energy along it
- dont need medium to travel, i.e can travel in vacuum
- electrically neutral
- electric+magnetic field oscillates at right angle (pependicular) to each other and to the direction of propagation
-undergoes reflection,refraction, diffraction & interference
-move with speed of light
3. ..its SPECTRUM????
the spectrum is a must to be remembered, could come out in Paper 1
shortest wavelength: Gamma ray
largest wavelength: Radio wave
lowest freqency: Radio wave
highest freqency: Gamma ray
4. ....its application ????
U need to remember at least 2 applications for each of the spectrum.
Watch these video..it might help u to memorize them.
Sound Wave Q & A
Q1: SPM2004/P1
transmitted from a boat to the seabed to
determine the depth, D, of the sea. The
speed of the ultrasonic waves in water is
1 500 m s ‘.The echo of the waves is received
2.0 s after the transmission.
What is the value of D?
A 375m
B 750m
C 1500m
D 3000m
thus D= (1500 x 2)/ 2
Q2: SPM2003/P1
Ahmad shouts in front of a high wall. He hears the echo of his voice 1.2 seconds
later.The velocity of sound in air is 340 m/s.What is the distance between Ahmad and
the wall?
A 204m
B 283m
C 340m
U 408m
E 816m
.. like in 2004 almost similar pattern of question came out in 2003. U can apply the same formula 2D = v x t ( D=distance, v=velocity, t=total time).
Q3: SPM2006/P1
Again..the same pattern came out in 2006
Diagram 21 shows a submarine transmitting ultrasonic waves directed at a big rock on the sea bed. After 10 seconds, the submarine detects the reflected wave.
Calculate the distance of the submarine from
the big rock.
[Velocity of ultrasonic wave =
1 560m/s]
A. 3.9 km
B. 7.8 km
C. 15.6 km
D. 31.2 km
E. 156.6 km
answer:
SPM: Analysing Sound Wave
Most of us love music, whether its rock, soul, jazz..joget, regardless of rhythm & genre.
But a few people appreciate the fundamentals behind those rhythm..which is the
… SOUND WAVE. …
In SPM u need to describe sound wave..( How ??)
a) sound is a longitudinal wave produced through vibrations in air.
b) Vibration of air molecules produce compression & rarefaction region
c) Sound needs medium (solid,gas, liguid) to travel, i.e it wont produce any
sound in vacuum like in outer space.. ( unlike starwars movie :) ..)
d) Sound travels fastest in solid..then liquid..and followed by air
Ok the diagram below helps u to understand sound wave better....
..next objective.. u'll also need to
1)Explain how the loudness relates to amplitude??
Answer:
- The loudness of sound is due to its amplitude.
- the higher the amplitude, the louder the sound
Ok..the amplitude of the sound wave is the amount of presssure applied on the air molecules.
- the more pressure applied/ the bigger the amplitude /thus the louder the sound.
Amplitude also related to ENERGY:
- the higher the amplitude,the louder the sound, the bigger the ENERGY
2) Relate pitch to frequency??
Answer:
- higher the pitch --> higher the FREQUENCY
In singing reality show, the juror always comment about their pitch..
so if the singer has "pitching lari" ..it means he/she does'nt produce enough frequency :)
To understand about pitching & loudness, better u visit this animation..but u need to key in
username:physics_form5
p/word:abcd1234
SPM: Interference Q & A
Q1 : SPM 2003/P1
The diagram shows the fringe pattern produced from Young’s double slit experiment using the monochromatic red light source.
What happens to the fringes if monochromatic yellow light source is used?
A. The bright fringes are wider than the dark fringes
B. The dark fringes are wider than the bright fringes
C. The distance between consecutive fringes decrease
D. The distance between consecutive fringes increase
it starts with red,orange,yellow,green,blue and so on.
from red to blue...the wavelength is decreasing,
So yellow wavellength is smaller,... by referring equation λ=(ax) /D ...
λ is directly proportional with x, thus x (distance between fringes)will also decrease.
Answer = C
Q2 : SPM 2004/P1
The diagram shows an interference pattern of two coherent water waves of sources, P and Q.
Which of the positions A, B, C or D, does destructive interference occur?
Answer: D
Q2 : SPM 2006/P1
Diagram 20 shows the interference patterns for water waves from two coherent source, S1 and S2.
Which of the following superposition of the waves at
shows the point Y?
answer= A (crest +trough = destructive interference)
SPM 2009 timetable not fixed yet
SPM timetable not fixed yet, says Alimuddin
By KAREN CHAPMAN
PUTRAJAYA: The timetable for the Sijil Pelajaran Malaysia examination has not been finalised, Education director-general Datuk Alimuddin Mohd Dom said.
He said the Malaysian Examinations Syndicate (MES) was studying the various complaints brought up by all parties.
“This includes recent complaints by several Form Five students that they were unable to register for certain subjects in the SPM exam due to a clash in the timetable,” he said.
Alimuddin said a tentative timetable was given to state education departments, district education offices and schools so that the dates could be looked at.
This would enable the MES to have more time to modify the timetable if there was a need, he said.
He said that any problems with the timetable should be brought up to the MES as it would need to be finalised by the end of this month.
The SPM exam will be held from Nov 19 to Dec 16.
MES policy management and development sector head Dr Jamil Adimin said all students taking the SPM must take six core subjects – Bahasa Melayu, English, Islamic Education or Moral Studies, History, Mathematics and Science.
“Students can choose the subjects they take in the exam as long as they also take the six core ones and ensure that there is no clash in the timetable,” he said.
There are no fees for students who take up to 12 subjects inclusive of the six core subjects, he said.
Dr Jamil added that they would be charged a fee if they opted to sit for more than 12 subjects.
http://thestar.com.my/news/story.asp?file=/2009/2/13/nation/3246018&sec=nation
SPM: Sound Interference
I just bought a surround home theatre speaker lately..now watching movie at home is awesome & more comfortable too.. thanx to those engineer who understands well the interference concept..
Now lets analyze the sound interference..all u need is two speakers which produce sound with same frequency (i.e coherent) and separated at distance, a
Ok..most important observation was that..u’ll hear loud & soft sound along the path
Loud = constructive interference
Soft = destructive interference
x = distance between 2 loud sound (or 2 soft sound)
Example:
Example:
Two loud speakers placed 2 m apart are connected to an audio signal generator that is
adjusted to produce sound waves of frequency 550 Hz. The detection of loud and soft
sounds as a person moves along a line is at 4.0 m from the loudspeakers. Distance between two loud places is 1.2 m
a) the wavelength
b) the speed
Tips: 1st u identify & extract the information given..such as
a = 2 m
f = 550hz
x = 1.2 m
Then apply in equation λ = ax …. u’ll get the wavelength
D
Next use v = f x λ to find the speed..try it out
(Answer: wavelength = 0.6m, speed = 330m/s)
Revise other topics:
Superposition
Light Interference
Water Interference
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