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A substance that attracts iron or iron like (\i oO substances. @ Y il Properties of Magnet - Every magnet has twe poles i.e. North and South. - Like poles repel each other. - Unlike poles attract each other. - Afreely suspended bar magnet aligns itself in nearly north-south direction, with its north poles towards north direction. Repel The area around a magnetic in which its magnetic force can be experienced. - Its SI unit is Tesla (T). - Magnetic field has both magnitude and direction. - Magnetic field can be described with help of a magnetic compass. - The needle of a magnetic compass is a freely suspended bar magnet. Characteristics of Field Lines - Field lines arise from North pole and end into South pole of the magnet. - Field lines are closed curves. - Field lines are closer in stronger magnetic field. Current Magnetic Field Magnetic Field It can be represented by concentric circles at every point on conductor. Direction can be given by right hand thumb rule or compass. Circles are closer near the conductor. Magnetic field « Strength of Current 1 Distance from conductor Magnetic field x ] It can be represented by concentric circle at every point. Circles become larger and larger as we move away. Every point on wire carrying current would give rise to magnetic field appearing as straight line at center of the loop. The direction of magnetic field inside the loop is same. Circular loop of wire carrying current Upward | Upward field lines field lines Downward Downward field lines field lines Factors affecting magnetic field of a circular current carrying conductor - Magnetic field « Current passing through the conductor 1 Distance from conductor - Magnetic field « - Magnetic field « Number of turns in the coil 1) It is a temporary magnet, so it can be easily demagnetized. 2) Strength can be varied. 3) Generally strong magnet. 4) Poles can be reversed. (matlab North pole ko South or South pole ko North pole bna skte h/ Poles ko reverse kiya ja skta h) 1) Can't be easily demagnetized. 2) Strength is fixed. 3) Generally weak magnet. 4) Poles can't be reversed. - Andre Marie Ampere suggested that the magnet also exerts an equal and opposite force ona current carrying conductor. - The displacement in the conductor is the maximum when the direction of current is at right angle to the direction of magnetic field. - Direction of force is reversed on reversing the direction of current. Force Magnetic Field Current Earth Wire (Green) - There are three kinds of wires used: (i) Live Wire (positive) with red insulation cover. Neutral Wire (Black) Live Wire (Red) (ii) Neutral wire (negative) with black insulation cover. (iii) Earth wire with green insulation cover. ani wane The Potential difference between Live and Neutral wire in India is 220 Voltage. Pole > Main supply > Fuse > Electricity meter > MCB > To separate circuits Neutral Wire 220 V » w = it - ATT Live Wire Earth|Wire Electric Pole Electric Meter = Main Switch Earth Protects us from electric shock in case of leakage of current especially in metallic body appliances. It provides a low resistance path for current in case of leakage of current. When live wire comes in direct contact with neutral wire accidentally. - Resistance of circuit becomes low. - Canresult in overloading. When current drawn is more than current carrying capacity of a conductor, it results in overloading. Causes of Overloading: - Accidental hike in voltage supply. 
