Electromagnetism, Electric Motor, Generator | Grade 10 Science DepEd MELC Quarter 2 Module 6

[Music] hi there have you seen a compass before have you tried using it to find directions if you have then you've done something that was first discovered by the chinese people in the 12th century historians believe that the chinese were the first to build compasses to help them navigate they made use of an important property found in certain materials that had been discovered centuries before magnetism magnetism the force exerted by magnets when they attract or repel each other became known to people many centuries ago they knew that the black metallic ore called lodestone has a property of attracting iron particles to it it is a naturally magnetized piece of the mineral magnetite over the course of centuries much of the mystery that once surrounded magnetism has been dispelled today the lodestone or the natural magnet is no longer familiar in the study of magnetism because practically all magnets nowadays are artificial a magnet is a substance that possesses magnetic properties it is a material or object that produces a magnetic field it attracts iron and faces the same direction when moving freely substances like iron steel nickel and cobalt are strongly attracted to magnets these substances are called ferromagnetic [Music] lodestones are magnetite or natural all natural magnets are permanent magnets meaning they will never lose their magnetic power an alnico magnet is a permanent magnet containing aluminum nickel and cobalt permanent magnets are used in radio speakers audio video devices and other electrical appliances on the other hand artificial magnets are materials that can be made into magnets artificial magnets are made by induced magnetism this is done by stroking ferromagnetic materials in the same direction several times with a magnet this process is called magnetization there are two types of artificial magnets temporary and permanent temporary magnets are magnets that aren't always magnetic but their magnetism can be turned on at will permanent magnets are those magnets whose magnetic strength never fades [Music] examples of permanent artificial magnets include refrigerator magnets and neodymium magnets neodymium magnets are the strongest permanent magnets commercially available anywhere in the world temporary magnets are those of soft iron that are easy to magnetize and they lose their magnetic property very easily an electromagnet is an example of a temporary magnet it is a magnet that can be switched on and off it is also used to lift heavy objects in industrial sites and in forwarding businesses every magnet has two poles you cannot produce a magnet with only one pole the areas of greatest magnetic force are called magnetic poles the end of the magnet that points north is called the north magnetic pole and the end that points south is the south magnetic pole opposite poles attract same poles repel this is another characteristic of magnets [Music] there are six elements that can be made into magnets iron nickel cobalt aluminum gadolinium and dysprosium none of these elements can be magnetized permanently to make a permanent magnet you need an alloy an alloy is a mixture of two or more metals the classic material for making a permanent magnet is steel an alloy of carbon and iron ships use compasses to find the correct course through vast areas of oceans where no land is in sight a ship's compass is a permanent magnet attached to a card marked in degrees that float in alcohol since magnets are flexible they can be made into many sizes and shapes there are several magnets hidden inside your house electric motors loudspeakers and television sets all contain magnets one magnet that is easy to detect is the magnet found on the door of your refrigerator [Music] the closer you bring two magnets together the stronger the force between them becomes move them apart and the force gets weaker if you move them further from each other you will eventually feel no force the force changes strength as you move within the magnet's magnetic field a magnetic field is the space around a magnet in which its force affects objects this is a magnetic field around a bar magnet the arrow heads show the direction of the magnetic lines of force which come out of the end pole and enter the s-pole the concentration of the lines of force at the poles shows that the field is strongest there on the other hand this is a magnetic field around a u-shaped or horseshoe magnet the shape crowds the lines of force together in between the two poles this means that the magnetic force between the poles becomes very strong this is also the reason why a horseshoe magnet can lift greater weight than a bar magnet [Music] when studying magnets during the 1820s michael faraday described magnetic fields through magnetic lines of force magnetic lines of force never overlap even when the poles of the two magnets are brought close to one another hans christian orsted in denmark was given a lecture on electricity to his students he closed a switch to demonstrate the flow of current there happened to be a compass nearby every time the professor closed the switch the compass needle turned orsted had then discovered that an electric current is surrounded by a magnetic field his discovery made him conclude that a current carrying wire produces a magnetic field this discovery led to orson's law so what is an electromagnet an electromagnet is a magnet that can be switched on and off it is a solenoid with a core the strength of an electromagnet can be made stronger by increasing the number of turns on the core shortly after orson's discovery michael faraday discovered that a moving wire through a magnetic field could produce an electric current he then concluded that when a wire is moved through a magnetic field a current is generated in the wire this process of generating current by the relative motion between a wire and a magnetic field is called electromagnetic induction [Music] at about the same time an american scientist named joseph henry made a similar discovery a current produced by a magnetic field is an induced current when we insert a bar magnet inside a coil current is induced inside it current is induced in such a way that its direction opposes the motion of the magnet changing the direction of the magnet changes the direction of the current now let's consider two coils such that the current flows through coil 1 and coil 2 is inside a closed loop in which current is induced the direction and magnitude of the current in coil 2 is dependent upon the vicinity and properties of coil 1. hence coil 1 is called the primary coil and coil 2 is the secondary coil changing the magnetic field inside one conductor induces magnetic fields inside another conductor this is called electromagnetic conduction the direction of current is confusing right fleming's right hand rule gives us an easy solution fleming's right hand rule gives the relation between the direction of current field and force the thumb gives the direction of the force the index finger gives the direction of the field and the middle finger gives the direction of the current so let's see its application on how generators work a generator operates on the principle of electromagnetic induction a generator is a device that converts mechanical energy to electrical energy suppose a b c d is a rectangular coil placed in the magnetic field the magnetic field is from north to south pole there are two rings r1 and r2 and two conducting brushes b1 and b2 when the coil is rotated we can find the direction of the current using fleming's right hand rule after half rotation c d starts moving up and a b starts moving down hence we can see that the current flows in the opposite direction from dc ba [Music] if the direction of the current changes after every half rotation this is called an ac or alternating current generator however in certain generators the direction of the current doesn't change these generators are called dc or direct current generators in dc generators one brush always stays in contact with the arm moving up and the other with the arm moving down the difference between ac and dc generators is that the direction of current in ac generators changes whereas it does not change in dc generators another important use of electromagnetism is in the electric motor an electric motor is a device that converts electrical energy to mechanical energy the opposite of electric generators a motor contains a movable electromagnet if an alternating current is supplied to the electromagnet its poles are reversed where it was once attracted by the opposite pole of a fixed magnet it will next be repelled this process is repeated many times each second [Music] there are many types of electric motors each is designed for a particular purpose or use they all operate on the principle of electromagnetism now let's wrap things up magnetism is the force exerted by magnets when they attract or repel each other a magnet is a substance that possesses magnetic properties it is a material or object that produces a magnetic field there are two types of magnets natural and artificial magnets artificial magnets are further classified as temporary or permanent magnets opposite poles attract and same poles repel [Music] electromagnetic induction is the production of an electromotive force across an electrical conductor in a changing magnetic field a generator operates on the principle of electromagnetic induction a generator is a device that converts mechanical energy to electrical energy an electric motor is a device that converts electrical energy to mechanical energy the opposite of electric generators that's all for now see you on our next video and don't forget to keep your minds busy if you like this video please subscribe to our channel and hit the notification icon for more videos like this

Channel: The Learning Bees

Views: 112,893

Keywords: The Learning Bees, Department of Education, DepEd, MELC-Based, Most Essential Learning Competencies, Science, MELC, Grade 10, Physics, Electromagnetism, how compass works, how electric motors work, how generators work, magnetism, lodestone, magnetic field, ferromagnetic, ALNICO, artificial and natural magnets, induced magnetism, temporary vs permanent magnet, magnetic poles, uses of magnets, michael faraday, Hans Christian Oersted, electromagnet, Fleming's Right Hand Rule, Joseph Henry

Id: 1f_AzGLciWg

Length: 14min 28sec (868 seconds)

Published: Tue Feb 23 2021