Analysing Electromanetic Induction

 Analysing Electromanetic Induction

 

Electromagnetic induction is the production of a potential difference (voltage) across a conductor when it is exposed to a varying magnetic field.


Michael Faraday is generally credited with the discovery of induction in 1831 though it may have been anticipated by the work of Francesco Zantedeschi in 1829.^[1] Around 1830^[2] to 1832,^[3] Joseph Henry made a similar discovery, but did not publish his findings until later.



Faraday's law of induction is a basic law of electromagnetism that predicts how a magnetic field will interact with an electric circuit to produce an electromotive force (EMF). It is the fundamental operating principle of transformers, inductors, and many types of electrical motors, generators and solenoids.^[4][5]



The production of Induced EMF or induced current without  using power supply but using relative motion between permanent magnet and currnet carrying conductor



There are two types of relative motion

                                  1) moving conductor in a permanent magnet

 



 

 

 

 

 

 

 

 

 

 

The direction of the induced current can be determined by using FLEMING'S RIGHT HAND RULE

 







T

2) Moving Magnet in a Solenoid

 

 

 

 

 

 

The direction of induced current can be determined using LENZ'S LAW

 

 





Inertia And Mass

Inertia and Mass

 

 

Newton's first law of motion states that "An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force."

 Objects tend to "keep on doing what they're doing." In fact, it is the natural tendency of objects to resist changes in their state of motion. This tendency to resist changes in their state of motion is described as inertia.

Mass as a Measure of the Amount of Inertia

All objects resist changes in their state of motion. All objects have this tendency - they have inertia. But do some objects have more of a tendency to resist changes than others? Absolutely yes! The tendency of an object to resist changes in its state of motion varies with mass.

 Mass is that quantity that is solely dependent upon the inertia of an object. The more inertia that an object has, the more mass that it has. A more massive object has a greater tendency to resist changes in its state of motion.

See the Inertia demonstration here:

 

 

 

 

 

The Negative Effect of Inertia

 

Principle of Conservation of Momentum

 Principle of Conservation of Momentum



One of the most powerful laws in physics is the law of momentum conservation. The law of momentum conservation can be stated as follows.

For a collision occurring between object 1 and object 2 in an isolated system, the total momentum of the two objects before the collision is equal to the total momentum of the two objects after the collision. That is, the momentum lost by object 1 is equal to the momentum gained by object 2.
 

Elastic And Inelastic Collision 

 

Observed The Video Clip

ELASTIC COLLISION

 

So the formula for Elastic Collision is:

 

 



 



INELASTIC COLLISION

 

 

 

 

The formula for Inelastic Collision is:

 

 

 

 



 

Explosion

 

 

 

 

 

Momentum is a commonly used term in sports. A team that has the momentum is on the move and is going to take some effort to stop. A team that has a lot of momentum is really on the move and is going to be hard to stop.



Momentum is a physics term; it refers to the quantity of motion that an object has. A sports team that is on the move has the momentum. If an object is in motion (on the move) then it has momentum.

Momentum can be defined as "mass in motion." All objects have mass; so if an object is moving, then it has momentum - it has its mass in motion.
The amount of momentum that an object has is dependent upon two variables: how much stuff is moving and how fast the stuff is moving.

 Momentum depends upon the variables mass and velocity. In terms of an equation, the momentum of an object is equal to the mass of the object times the velocity of the object.

Momentum = mass • velocity

In physics, the symbol for the quantity momentum is the lower case "p". Thus, the above equation can be rewritten as

p = m • v

where m is the mass and v is the velocity.

The equation illustrates that momentum is directly proportional to an object's mass and directly proportional to the object's velocity.

 

Express your understanding of the concept and mathematics of momentum by answering the following questions. Click the button to view the answers.

1. Determine the momentum of a ...

a. 60-kg halfback moving eastward at 9 m/s. b. 1000-kg car moving northward at 20 m/s.
c. 40-kg freshman moving southward at 2 m/s.
 

Answer 

2. A car possesses 20 000 kg ms-1 of momentum. What would be the car's new momentum if ...

a. its velocity was doubled.b. its velocity was tripled.
c. its mass was doubled (by adding more passengers and a greater load)
d. both its velocity was doubled and its mass was doubled.

Answer

 

Free Fall- Fall Without Air Resistance

Without Air Resistance

Suppose that an elephant and a feather are dropped off a very tall building from the same height at the

same time. Suppose also that air resistance could be eliminated such that neither the elephant nor the

feather would experience any air drag during the course of their fall. Which object - the elephant or the

feather - will hit the ground first? Many people are surprised by the fact that in the absence of air

resistance, the elephant and the feather strike the ground at the same time. Why is this so? Test your

understanding by identifying the following statements as being either True

(T) or False (F)

 .

1. The elephant and the feather each have the same force of gravity.                             (T)  or  (F)

2. The elephant has more mass, yet they both experience the same force of gravity.      (T) or (F)

3. The elephant experiences a greater force of gravity, yet both the elephant and the feather

have the same mass.        (T) or (F)

4. On earth, all objects (whether an elephant or a feather) have the same force of gravity.     (T) or (F)

5. The elephant weighs more than the feather, yet they each have the same mass.                  (T) or (F)

6. The elephant clearly has more mass than the feather, yet they each weigh the same.          (T) or (F)

7. The elephant clearly has more mass than the feather, yet the amount of gravity (force) is the

same for each.                   (T)   or   (F)

8. The elephant has the greater acceleration, yet the amount of gravity is the same for each.  

(T)   or   (F)

 

 

 



Bengkel Peningkatan Panitia

Selamat Datang Ke Dunia Fizik. Dunia Yang Penuh Keseronokkan

 

Bracelet For Human Rights Workers Sends Kidnapping Alerts To Facebook and Twitter

Bracelet Alarm Natalia Project, Civil Rights Defenders

Activists and aid workers who document government abuses or monitor elections often risk abduction by those who oppose their work. Now one organization has developed a gadget to help.
Stockholm-based Civil Rights Defenders is distributing a bracelet that sends out "Help!" messages when its wearer activates it, or if someone pulls the bracelet off its wearer forcefully, the BBC reported. The bracelet has a GPS tracker and will send information about the wearer's identity and location to nearby workers who could come to the rescue. The Civil Rights Defenders headquarters also gets a notice.

At the same time, the bracelet posts messages to Twitter and Facebook, which Civil Rights Defenders says will make repressive regimes warier of garnering international condemnation for kidnapping activists.

The advocacy group hopes to give out 55 bracelets within the next year and a half.
Civil Rights Defenders says the bracelet was inspired by the case of Natalia Estemirova. Estemirova documented human rights abuses in Chechnya in the northern Caucaus region. In 2009, she was abducted and shot in the head.

Interested folks can sign up to get alerts from the Civil Rights Defenders bracelets. People may also donate to the program.

Longer Life Lithium Sulphur Batteries

Longer Life Lithium Sulphur Batteries

 

Image: The scientists at IWS have optimized the design of anode and cathode for lithium-sulfur batteries.

Researchers have developed a lithium-sulfur battery with a significantly increased lifespan—which could help make electric vehicles more attractive to consumers.

Lithium-sulfur batteries are more powerful and less expensive to manufacture than lithium-ion batteries, but they suffer from a limited lifespan. In an attempt to increase this lifespan, the team designed the battery with an anode made of a silicon-carbon compound instead of the typical metallic lithium, which improved stability. The cathode is made from elemental sulfur, and so costs less to manufacture than the conventional cobalt cathodes. The result was a button-cell battery with a lifespan of up to 1400 cycles, compared to the 200 cycles of current options.

According to Dr. Holger Althues, head of the research team, the new batteries could also have applications in smartphone and could even help to make electric flying vehicles a reality one day.

How To Grab A+ In Physics?? - Testimonial From A1 Student

Although I scored an A1 in Physics for SPM, I am not exactly the right person to be asked, "how did you do it?" So, I posed the question to my friend, Jasmine, instead to see what she had to say. Jasmine and I have known each other for 5 years (yes, throughout my secondary school years) but, our fathers know each other longer than that! Anyway, here is what she had to say:

Firstly, Physics is very different compared to the other subjects. Physics is one of the toughest Science subjects for many people. Physics is more to the Maths side as it is mostly calculations, formulaes and principles.. Biology is 100% memorising, Chemistry is 50% calculation, 50% memorising, Physics on the other hand is 100% calculation and formulaes. The study of Physics is very deep and it involves a lot of techincal details: heat, electricity, electronics and so forth. Every minor detail is important and that makes the subject complex and sometimes even tedious. Nevertheless, once mastered, Physics is very useful for survival purposes in our daily life.

One very important thing in Physics is understannding. You must understand what you are learning, not just memorise for the sake of exam. Physics is actually an easy subject to study. All you must know are the formulaes and principles involved.. What usually happens is the teacher will twist the questions and asked them from different angles. That is when it becomes tough. What you must remember is the basic pronciples involved. No matter how tough the question is, in the end, it will always go back to the basic principles.

I would recommend a good revision book for this subject as the school textbook alone is not enough to score. Pay attention in class and ask questions whwnever you don't understand. Do not be scared or shy to question your teachers as it is necessary for you to know in detail about Physics. For eg:
Where did the formulaes come from, how are they derived, how are the variables involved connected to each other, conversion of units and many more.

Master your calculations and make sure you choose the right formulaes for each question. This can be a problem sometimes. Physics is not a mugging subject, you cannot simply study it by the book. You must attempt questions from workbooks and do a lot of exercises. Only then you will be exposed to a wide range of different ways questions can be asked. Hence, you will be able to answer various types oy questions no matter how tough they may seem.

Interest plays a vital role in scoring in this subject. You must show keen interest in studying Physics. Most people dislike the subject as it is far more complicating then the other Science subjects. Therefore, they make no effort to master the subject.

Finally, try attempting the past year questions for Physics. Analyse the questions and topics that have come out in the previous years. SPM questions are always very similar, so chances of the same type of questions coming out every year is very high. Please take note, same type of questions, not same questions. Make sure that you are able to do all the past year questions. If so, you will not have a problem during the actual exam.

It is very important for you to understand in Physics. You MUST know what you are studying. Only then will you be able to score in the subject. Physics is not a difficult subject. I feel that it is much easier than Biology and Chemistry, bur it requires a lot of patience, interest and understanding.

NEXT, I asked her what type of reference books she would recommend. Also asked why she was very interested in the subject.

I don't know what are the reference books they have nowadays for Physics but I would recommend either Success or Focus. I found both quite good. But you can also check out the others that are there now.

I was always interested in tools and mechanical stuff ever since I was small. I love playing with my father's gadgets even now and I suppose that's why I love Physics. This is something that has to come from within I guess.
So, there you have it. Feel free to add on to the above mentioned points. One question for all of you out there, how do you spark an interest in Physics?

SPM Tips: Man Jadda Wa Jadda

Assalamualaikum..

Today i just wanna share one of my xperience with a student recently. We discussed his problems about physics, especially the section B & C,paper 2. He asked me for tips, i told him any tips wont do u any good if u didn't practice. He complained, i've no time , midterm xm is just within 2 days. I need 'instant tips'. By looking at his answer i wondered what he'd been doing for the past 1.5 years?

I'm not trying to be rude, but..Hey..what do u xpect..do u think studying physics is like cooking 'mee maggi'?

Can u xpect by having thousand tips just b4 the xm will give u an 'A1' or atleast'A2'?
This is a typical malaysian students' attitude..if xm is getting near they r lookin for tips.
In the end they dont treasure the virtues of knowledge that they supposed to appreciate. Let say even though they've scored a good results ..i'm sure they will be having problems studying in university. Coz in university u need to appreciate what KNOWLEDGE is..otherwise u'll end up like other graduates who is hopeless to find job in this competitive market.

Some said what important is to get an A.. YES its true. Some said if u have money, u can buy thousand TIPS through internet...but still it wont guarantee you an A. The truth is u need to appreciate wat u've learned. Its not only applicable to physics but other subjects as well. Sometimes u need to learn the hard way but in a smart approach.
As people said 'NO PAIN NO GAIN'

Another important learning outcome under subtopic 3.2 is to describe:
How a direct current motor works??..this such question can come out in SPM essay paper2

- to describe this, 1st u need to know how the diagram of dc motor looks like.
- then u need to label it, such as which one is the commutator, carbon brush and other component.

Description:

• A direct current (DC) motor which consists of a coil of many turns uses the magnetic turning effect.

• The current flows into the coil through a pair of carbon brushes. The carbon brushes push against commutator.

• then, the commutator changes contact from one brush to another while the coil is turning. This is to keep the coil rotating continuously.

The next thing u need to know is the factors that affect the speed of rotation. The speed of rotation can be increased by:

• increasing Amount of Current
• increasing the strength of magnetic field
• increasing No. of coils

basically, if u understand the whole concept, u can build your own electric motors..watch these videos..

Physics Is Wonderful.. But Before Studying Physics We Need Some Basic Skills.

Based on my experience in teaching physics, almost every year i received complaint from form4 student that physics are among their toughest subject.Sometimes they said it is too hot to handle.Some said they can't even relate what they 've learned in science PMR. Sadly to say it happened also to those who got straight A in PMR. Sometimes i wonder how did they get A in science but really 'blur' while studying physics.

Anyway,to learn physics u need to be mentally prepared. U need certain thinking skills to enhance your understanding on this subject.Well..what kind of skills do u need in order to study Physics for SPM? Here i list down some of the skills needed :

1. Mathematic skills:
It is not the add maths skills..but basic skills u learned in modern maths , i.e in algebra,standard form,ratio,gradient of straight line graph,variation,trigonometri. If u are very weak on those topic, u'll find it very hard to understand certain physics concept.

2.Logical reasoning
It is very helpful if u have the skills to apply logical reasoning in order to get solution from a given physics problem. For example, if u are asked to design a car that can accelerate faster..Logically we can say that the heavier the car the slower it will move. So u have to make sure that the car body is made from a lighter materials.
It is logic..isnt it

3. Problem solving skills
If u joint scout team..u might have been taught to solve a situation in a camping trip. For example, u are asked to build a tent using bamboos. U've got to ensure that the tent is strong enough to overcome stronger wind. U've got to gather some information & design an action plan to do it.Then start to prioritize them so that u know which action need to be taken first.Basically all of these activities require a good problem solving skills which is not taught in most of the SPM text book.

4.Good Study skills
Some student studied very hard..but they dont study smart. In the end they dont get the result they want. . U need a good study habit and u've got to be smart & creative. For example while doing your own notes,use bright colors,mind map diagrams or cartoons to visualize your physics notes..make physics a fun subject to learn. Another suggestion is to study in a group. Sometimes by having a study group, u can actually solve physics problem in short time compared doing it alone. Two head is better than one :)

There are maybe many other skills that i m not able to mention in this post..Whatever it is, my final words to these form 4 students..DO not HATE this subject . Try to get to know it with passion..who knows one day u'll fall in LOVE with it :)