Presentation on theme: "NEETI SANON www.udgamschool.com Fun with Magnets NEETI SANON www.udgamschool.com."— Presentation transcript:
1 NEETI SANON www.udgamschool.com Fun with MagnetsNEETI SANON
2 What is a magnet ?Any substance which attracts pieces of iron towards itself.And always comes to rest in N-S direction is known as a magnet.
3 What is magnetism ?The Property of a magnet to attract things made up of Iron, Cobalt or Nickel is known as magnetism.
4 What is Magnetic Field?The area surrounding the magnet in which magnetic force is exerted to attract iron is known as magnetic field.The magnetic lines of force originate from the North Pole of a magnet and end at its South Pole.
6 Magnetic PolesThe ends of the magnet where the magnetic force is concentrated are called magnetic poles.Each magnet has 2 poles : North & South pole.
7 Types of Magnets There are 2 types of magnets : 1) Natural Magnets: They have low magnetic power.Eg : Magnetite, lodestone.2) Artificial Magnets :They have a strong magnetic power.They are found in different shapes.
18 Induced Magnetism Permanent magnet Soft-iron bar Permanent magnet brought Soft-iron bar becomes annear to soft-iron bar induced magnetIn magnetic induction, an opposite pole is always induced.– 2 unlike poles facing each other is observed during magnetic induction.S NS NS N
19 Storage of Magnets - Using Keepers The “free poles” near the end of magnets repel each other.As time passes, the magnet becomes weakerTo prevent this weakening, bar magnets are stored in pairs by using keepers– 2 pieces of soft iron across the ends of the bar magnets.
20 ElectromagnetismPPlace the steel object inside a coil of wire (a solenoid).• Pass a direct current through the solenoid.• A magnetic field isproduced on the solenoid.• The steel rod is now placed inside a magnetic field.• When the current is turned off the steel rod is found to be magnetized
21 Electromagnetism Right-hand Rule. – Wrap the fingers around the coil form in the direction of the current flow in the solenoid.– the thumb will point indirection indicating the end which becomes the N-pole.
22 Earth is a big MagnetWe know that at the centre of the Earth lies a molten metallic iron rich core.The outer portion of this core is molten.We also believe that this core is spinning.It is believed that the metals in the core have many loosely bound electrons and that these particles can conduct electricity.It is this mass of moving electrons which produces the magnetic field.
23 Think of the Earth as having a gigantic bar magnet buried inside. In order for the north end of the compass to point toward the North Pole, you have to assume that the buried bar magnet has its south end at the North Pole.
24 Magnetization by Stroking (Single-Touch) This method is derived fromapplying the processes ofMagnetic induction– Note the polarities of both thepermanent magnet & steel barthat is to be magnetized– This form of magnetism gained isweak but permanent
25 Magnetization by Stroking (Double-Touch) Two permanent magnets areused in this method.– Note of the polarities of thepermanent magnets & theirinduced ends of the steel bar– This form of magnetismgained is also weak butpermanent.