I have entitled my blog “READ AND DISCOVER ELECTROMAGNETIC INDUCTION” because when someone is going to read this blog they might discover something about electromagnetic induction which they don’t still know. READ. READ. READ. And DISCOVER the concept of ELECTROMAGNETIC INDUCTION.

In this section of my blog, I will be talking some things about the Electromagnetic induction and some concepts that has concern on this topic- What I knew about it, What i learned, How i learned and a Reflection can be found found in this blog of mine. Take time to read and enjoy:).

WHAT I KNEW?

Before we have tackled this topic, what is set on my mind is that electromagnetic induction is a combination of electricity and magnetism or simply magnets. I also know that the concept of electricity and magnetism before were separate and unrelated phenomena but with the help of the experiments of the great people such as Faraday this two concepts were combined.

WHAT I LEARNED?

Magnetism (Magnets)

The easiest way to define magnet is that these materials has the ability to attract metals. “Magnets were considered as the first cousin of electricity”. in that statement you can say that magnetism and electricity are very much related.

Classification of Magnets

Magnets can be classified into two groups- the natural magnets and the artificial magnets. Natural magnets are the ones that can be found in nature which so called as lodestones or magnetite. While the artificial ones are made by humans by using magnetic substances such as iron, steel and cobalt.

Magnetic Poles

Magnets has also their own directions or so called poles. Some magnets have labelled poles such as the bar magnet and U- magnet. This directions or poles are the North and South pole. The pole that points towards the north is called the North-seeking pole. While the other one that points towards the south is called the South-seeking pole.

Fun Facts:

Magnets always have two directions or poles. The North and South pole can never be isolated, they always come in pairs.
When a magnet is break into two each half would still be a magnet.
Legends says that magnetism comes from the word “Magnes”, the shepherd whose staff got attracted to a lodestone in Mt. Ida.
Opposite poles always attracts each other and same poles always repels each other.

Magnetic Field

Magnetic field is defined as a region that surrounds the magnet in which the magnet is capable of exerting a force on a magnetic material.

In 1830, Michael Faraday introduced the idea that magnetic field is made up of line of forces. Magnetic field lines points from north to south pole.

Magnetic Flux

It is defined as the number of lines of force on the magnetic field. Its unit is weber, abbreviated as Wb.

φ = BA cos θ

Magnetic Field Intensity

It is the flux per unit area perpendicular to the field. Its SI unit is tesla, named after Nikola Tesla. A letter T denotes the unit tesla.

Β=φ /A

where B is the magnetic field intensity in tesla (T), φ is the flux in weber (Wb), and A is the area in square meter (m²).

1T = 1 Wb/ m²

Tesla, being a unit of magnetic field intensity, is equivalent to N/Am.

1T = 1 Wb/ m² = 1 N/Am

The Right Hand Rule

Rule 1– Grasp the wire with the right hand in such a way that the thumb points to the direction of the conventional current. The fingers curl in the direction of magnetic field.

Another version of the right hand rule is more convenient to apply in case of loop of wire and a solenoid. A solenoid is simply a long coil of several turns of wire.

If fingers of the right hand are curled in the direction of the current, then the thumb points to the N pole of the field.

Rule 2- Point your thumb to the direction of the current or velocity. Point your fingers to the direction of the magnetic field. Your palm will point to the direction of the forces.

Electromagnetic Induction

Based from what i have learned in our discussion Electromagnetic induction is phenomena in which electric current is generated by varying magnetic fields. It can also be defined as the production of potential difference (voltage) across a conductor when it is exposed to a varying magnetic field. The current and the emf produced are called induced current and induced emf respectively.

There are two laws describing electromagnetic induction. First is the law of Faraday, it states that whenever whenever there is a change in the magnetic flux in a circuit, an induced current is produced. The induced emf is is proportional to the rate of change of magnetic flux. While on the Lenz’s law it states that the induced current flows in a direction so as to oppose the change causing it.

Combining the Faraday’s law and Lenz’s law, we have the formula

E= -N ΔΦ/ Δt

where E is the induced emf, N is the number of turns , ΔΦis the change in flux equals to ΔΦfinal-ΔΦinitial, Δt is the time elapsed. The negative sign means that the induced emf sends current in a direction as to oppose the change in flux causing it.

Factors that Affects the Induced Emf

Number of turns (N)- The more the number of terms the higher the induced emf.

Number of turns (N)	Induced Emf
Less	Lower
More	Higher

The relationship of Number of turns (N) and the induced emf is directly proportional.

2. Speed in which the magnet is plunged or the time elapsed.

Speed in which the magnet is plunged	Induced Emf
Slow	Lower
Fast	Higher

When talking about speed of plunging, the faster you plunged the magnet the greater the induced emf. Their relation ship is directly proportional.

Time	Induced Emf
less	Lower
more	Higher

When talking about time it talks about how much time is consumed when the magnet is plunged. That is why the lesser the time consumed the higher the induced emf. Their relationship is inversely proportional.

3. Magnetic Flux affects the induced current but its magnitude or value is also affected by three factors, these are Magnetic field (B), area (A) and the angle θ.

Magnetic flux	Induced Emf
Lower	Lower
Higher	Higher

The magnetic flux and induced emf is directly proportional to each other. As one of them increases the other one also increases.

How does speaker and microphone works?

SPEAKERS

Inside a speaker:
1. Cone
2. Electromagnet (coil)
3. Permanent magnet

Inside a speaker, an electromagnet is placed in front of a permanent magnet. The permanent magnet is fixed firmly into position whereas the electromagnet is mobile. As pulses of electricity pass through the coil of the electromagnet, the direction of its magnetic field is rapidly changed. This means that it is in turn attracted to and repelled from the permanent magnet, vibrating back and forth.

MICROPHONE

A speaker in reverse to convert sound into an electrical signal.

HOW I LEARNED?

“TELL ME AND I FORGOT. TEACH ME AND I REMEMBER. INVOLVED ME AND I LEARN” – Benjamin Franklin

As a student, curiosity is in us. by exploring what we wanna learn, by knowing the things which we are curious of we LEARN. And the best way for us to learn things is to experienced how it is done.

So, i have learned those many things i have discussed on the upper part of my blog because i have been involved in the class of our adviser, Mr. Lexter Supnet. With the proper teachings and guidance in our activities, electromagnetic induction has become more clear to me.

One of the activity he has given to us is determining the factors affecting the induced emf. What we did is that we have gather the materials such as solenoid, bar magnet, galvanometer, and copper wire.

The first one that we have observed with our group is the effect of the number of turns of the wire. We made a lesser turns of the copper wire and we also made one which has more turns of wire. As a result, we have seen that the more the turns of wire the greater the induced current.

Image result for coiled copper wire — Coil of Copper Wire

The second one we have observed is the speed in which the magnet is plunged or can also be called as time of plunging but will have different relationship on the induced emf. What we did is that we plunged the bar magnet on the solenoid with a slower speed and a faster speed. As a result, we have seen that speed of plunging is directly proportional to the induced current.


Itusok mo pa Jeh

What he other group has used as a variable to observe is the time of plunging. They have observed that the lesser the time consumed in plunging the higher the induced emf. thus, the time elapsed and the induced emf is inversely proportional. We have different data because the variable we have used is not the same. It is more advisable to used time elapsed as variable because it is the one used in the formula.

The third variable that affects the induced emf is the magnetic flux. We are not able to observed the effect of this but through listening to the discussion during the checking of our activity papers we have learn about it.

I have also learn electromagnetic induction by reading the module that Sir Lex has given to us. So simply, i have learned many things about electromagnetic induction because of him.

Reflection

By listening to our teacher’s discussion and participating in group activities, my learning in this topic might help me someday when i am in college. Not only in college but it might also help me in my daily life. Because of the things i have learned right now , you don’t know I might invent something in the future hahaha char. We might not know what will happen to us in the future that is why the best thing to do is keep the learning in you. Learning is one of the thing that not anyone can still. Keep them. I’m sure they will be useful someday.

REFERENCES