std 10 - electromagnetism
TRANSCRIPT
Standard/ Class/ Grade - 10 SSC, CBSE; - 8 ICSE All about Electromagnetism
Gurudatta K Wagh
Standard 10, Chapter 5, All about Electromagnetism
5.1 Magnetic lines of force
5.2 Magnetic field due to current carrying conductor5.2.1 Right – Hand Thumb Rule5.2.2 Magnetic field due to a current through a circular loop5.2.3 Magnetic field due to current in a solenoid
5.3 Force on a current carrying conductor in a magnetic field
5.4 Electric motor
5.5 Electromagnetic induction5.5.1 Fleming’s Right – Hand Rule (for generators)5.5.2 Types of current – Direct and Alternating current
5.6 Electric Generator
5.7 Domestic electric circuit5.7.1 Safety measures in using electricity5.7.2 Short circuiting and overloading
Standard 10 Chapter 5 All about Electromagnetism
Electromagnet - A magnet in which magnetism is induced with the help of electricity
Uses - Transformer, door bell, speaker, water pump, generator, radio, television antenna
5.1 Magnetic lines of force/ Magnetic field linesPath along which the unit north pole moves in a magnetic field
Properties
1.Closed continuous curves, start from north pole and end on south pole2.Tangent at any point on them gives the direction of the magnetic field3.No two magnetic lines of force intersect4.They are crowded where the magnetic field is strong. They are far from each other where the field is weak
Hans Christian Oersted Electricity and magnetism are related
If a current is passed through a wire (conductor), electric field is produced near it
A compass needle is a small bar magnet
5.2 Magnetic field due to current carrying conductor
1.Magnitude of the field produced at a given point is directly proportional to the magnitude of the current passing in the wire2.Magnetic field produced by a given current in the wire decreases as the distance from the wire increases
5.2.1 Right-hand thumb rule
Thumb points towards the direction of current and curled fingers give the direction of the magnetic field
5.2.2 Magnetic field due to a current through a circular loop
Magnetic field produced by a current carrying wire at a given point depends directly on the current passing through it
5.2.3 Magnetic field due to current in a solenoid
Solenoid A coil of many turns of insulated copper wire in the shape of a cylinderHas all the properties of the field produced by a bar magnetCan magnetise a piece of rod of a given material
5.3 Force on a current carrying conductor in a magnetic field
Andre Marie Ampere The magnet also exerts an equal and opposite force on the current carrying conductor
1.A force is exerted on the rod carrying the current when placed in a magnetic field
2. The direction of the force depends on the direction of the current and the direction of magnetic field
3. Displacement of the rod is maximum when the direction of the current is at right angles to the direction of magnetic field
Fleming’s left hand rule (for motors)Forefinger – direction of the magnetic fieldCentral finger – direction of the currentThumb – direction of the motion of the conductor
How to study the structure of matter?Current is a flow of charge. Moving charges in a magnetic field would experience a force. This property is used to accelerate charged particles to very high energies. These high energies of the particles are used to study the structure of matter.
Electric current produces magnetic field even if the current is weak.
Magnetic resonance imaging (MRI), nuclear magnetic resonance imaging (NMRI), or magnetic resonance tomography (MRT) is a medical imaging technique used in radiology to image the anatomy and the physiological processes of the body in both health and disease. MRI scanners use strong magnetic fields, radio waves, and field gradients to form images of the body.
5.4 Electric motorConverts electrical energy into mechanical energyPrinciple – A current carrying conductor placed in a magnetic field experiences a forceWorking – The coil rotates with the help of electrical energyUses – mixer, blender, refrigerator, washing machine, fans, hair dryer, tape recorder, blower, cars, rolling mills, cranes, lifts, trains
Magnetic levitationTrains float on railsA current passes through the electromagnets in the track and on the trainMagnetism produced lifts the train upwards
5.5 Electromagnetic induction1. If a conductor is moving inside a magnetic field or magnetic field is changing around a fixed conductor, electric current is generated – Michael Faraday2. The motion of a magnet with respect to the magnetic coil or if coil is moved with respect to the magnet, potential difference is induced, which sets up an induced electric current in the circuit.3. Potential difference is induced in the coil 2 whenever the electric current through coil 1 is changing.4. Coil 1 is called as “primary coil” and coil 2 is called as “secondary coil”.5. The process by which a changing magnetic field in a conductor influences a current in another conductor is called “Electromagnetic induction”.
Fleming’s right hand rule (for generators)Forefinger – direction of the magnetic fieldCentral finger – direction of the currentThumb – direction of the motion of the conductor
The induced current is found to be the maximum when the direction of motion of the coil is at right angles to the magnetic field.
A galvanometer is an instrument which is used to detect the presence of current in a circuit.
Michael Faraday electricity could produce rotary motion. Electric motors work on this principle. Relative motion between a magnet and a coil of wire could induce electricity in the coil, an idea which gave birth to modern generators.
5.5.2 Types of current Direct and Alternating currentAdvantage of AC over DC is that electric power can be transmitted over long distances without loss of much energy.
Direct current Alternating currentThe magnitude and direction is constant.
The magnitude and direction reverses periodically.
Cannot be used on a large scale.
Can be used in electric household appliances.
The frequency DC is zero The frequency of AC is about 50Hz.
5.6 Electric GeneratorConverts mechanical energy into electric energy.Principle – works on the principle of Electromagnetic induction.
Types of electric generator1) AC generator - works on alternating current.2) DC generator - works on direct current.
AC generator DC generator
5.7 Domestic electric circuitWires are of 3 types –a)Red - Phase wire (live wire)b)Black - Neutral wirec)Green - Earth wire
Connected to an electric meter installed inside the house or a factory.Potential difference between the live wire and neutral wire is 220V – 250V.Electric meter to the main switch.Main switch is placed in the path of live or phase wire.
5.7.1 Safety measures in using electricity
a)Electric fuse is a safety device used to save the electrical appliances.b)Wear gloves made of insulated material and rubber soled shoes.c)Insulation of the wire must be checked periodically.d)Earthing – One end of copper wire is connected to the metal case of the appliance and the other end is connected to the copper plate buried deep inside the earth.
5.7.2 Short circuiting and overloading
A) Short circuitingLive wire and neutral wire come in
direct contact, short circuiting takes place. Resistance
of the circuit becomes very small, huge amount of current flows through it.
Produces a large amount of heat and raises the temperature. The circuit catches fire.
B ) OverloadingFlow of large amount of current in the
circuit beyond the permissible value of current.
This can be avoided by not connecting many appliances at a time in the circuit.
THANK YOU
SSC Std 10th TextbookCBSE Std 10th Textbook
YouTubeGoogle
Wikipedia
Suggestions and Appreciations welcome