Superconductor

Superconductor is one of the most fascinating features in physics. This concept allows a bullet train to float a few milimetre on its rail, causes less friction to make it moves at 'super' speed. However we're unlucky coz in SPM we wont study abt it in detail.If u wanna pursue your career in electronis,electrical or mechanical engineering.. i think its good to be exposed about it as early as possible.


To understand superconductor, u must understand the word conductor itself. Conductor is like a wire which can conduct electricity. Usually a wire has resistance. Resistance comes from the word, 'resist'..i.e it resists the flow of electrons or current. Different wires has different resistance.But bear in mind, not all conductors are wires.


So..how about superconductors?? 


Under low temperature, the resistance of a conductor decreases. But under extremely low temperature, some conductors has almost NO resistance...i.e it has ZERO resistance. If this condition is achieved, the conductor now has transformed itself into Superman :) ops!!...it supposed to be SUPERCONDUCToR.


Kalau nak senang faham..bayangkan superconductor ni mcm sebatang highway ..
Tapi katakanlah highway tu sekarang bapak u yang punya :)
So bila hari raya, disebabkan highway PLUS tu bapak kita yang punya. So kalau u jalan kat highway tu takde siapa pun yg nak kacau..takde traffic jam..takde polis...i.e takde apa2 halangan. Kalau u nak main skateboard kat situ pun boleh :) 
Senang citer kita kata highway tu takde "resistance". (ZERO RESISTANCE)


Kalau nak tau lebih detail pasal superconductor ..Wajib tgk video2 ni!!

Factors Affecting Resistance

In this post, i wanna discus the next section 2.2 learning outcome which is:

1. Factors that affect resistance. What are the factors???

i. Length(l) of conductor :
R is directly proportional with l. The longer the length the bigger the resistance.

Just imagine if you need to choose between1000m & 5000m marathon, which one will cause bigger resistance to you?

ii. Area(crossectional area,A) of conductor:
R is inversely proportional with A i.e the bigger the area the smaller the resistance

iii. Temperature(T):
R is directly proportional with T
The higher the temperature, the bigger the resistance.

iv. Type of conductor
Resistance depends on type of conductor used, different metals have differen resistive value.
Silver has less resistance than copper..but usually copper is widely used in a lab coz its cheaper.

Please check out the experiment involved on factors affecting resistance in yr text/reference book.

2.The next outcome, u must be able to-
Describe superconductors:
Superconductors are materials that have almost ZERO resistance as the temperature
decrease towards absolute zero (-273 degree celcius).

Superconductors can carry current without loss of energy..thus the transfer of energy is very efficient.

Its application is widely used in levitated train (bullet train).

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).

From this experiment u shud be getting a straight line graph of Voltage(V) vs Current (I). This experiment can come out in paper3 or paper2.
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.

V α I

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