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Electricity and magnetism

This document provides an overview of electricity and magnetism. It discusses electric and magnetic fields, how magnetic fields are produced by electric currents, and some applications like electromagnets and motors. The key topics covered include electric charge, electric fields, magnetic fields, electromagnetism, and basic electric circuits. Hands-on activities are also included to demonstrate these concepts.

Education◦
ELECTRICITY AND MAGNETISM A JOURNEY TOWARDS THE SMALLEST PART OF MATTER
TOPICS • Electric fields and magnetic field • The presence of magnetic field in current carrying wire.
OBJECTIVES: • Explain the behavior of charges in the electric field. • State that a magnetic field exists around a current carrying wire. • Explain how electricity is related to magnetism and the nature of magnetic field.
ACTIVITY Group Activity Group 1 Charge Hockey Group 2 Magnetic Field Group 3 Magnetic field Group 4 Magnetic field Group 5 Charge Hockey
EM Induction Magnetic Field (B) Magnetism B due to I Force of B on I Electromagnets Motors Faraday’s Law •Generator/Transformer •Power Transmission • Magnetic Field • Magnetic forces • Electrical Power • Electrical energy Electric circuit/connection Ohm’s Law Electric Charge Electric Force Electric Field Electric Potential WORLD OF ELECTRICITY AND MAGNETISM Electric Current (I) Electrostatics Magnetic Field and Current • Positive and negative electric charges • Attraction/Repulsion between charges  Electric current  Electric circuits (at home)
• Involves… Electric charges The forces between them  and their behavior in materials Electrostatics
THE CHARGES… •Everything is made of atoms which contain POSITIVE particles called PROTONS and NEGATIVE particles called ELECTRONS. Proton (+) Neutron Electron (-)
•An atom will usually have the same number of positives and negatives •This makes the atom NEUTRAL. Proton (+) Neutron Electron (-)
WHAT IS INSIDE AN ATOM? Thomson’s Plum pudding model Rutherford model Rutherford Bohr model Charge cloud model Quantum model of the nucleus
ELECTRICAL CHARGE • Electric charge is given the symbol q Electrons are the charge carriers that flow in an electrical circuit –from the negative to positive terminals.
ELECTRICAL CHARGE • Charge is measured in Coulombs • which is given the symbol C
ELECTRICAL CHARGE • The charge on a proton is 1.6 x 10-19C • which is the same size as the charge on an electron.
FUNDAMENTAL RULE OF THE BASE OF ALL ELECTRICAL PHENOMENA Like charges repel; Opposite charges attract. Source; Paul Hewitt, (1998). Conceptual physics, CA: Saunders Publishing
CHARGING PROCESS • Charging by friction and contact • Charging by induction • Charge polarization
ELECTRIC FIELDS AND POTENTIALS
ELECTRIC FIELD The space around every electric charge is filled with an electric field-a kind of aura that extends through space.
ELECTRIC POTENTIALS Electric Potentials (volt): work done per unit charge (Bringing a very small positive charge from one point to the other.) 1volt = 1 JOULE COULOMB
POTENTIAL DIFFERENCE OR VOLTAGE (V) A 9 V battery will give how much energy to each coulomb of charge passing through the battery? 9 J
POTENTIAL DIFFERENCE OR VOLTAGE (V) A 1.5 V battery will give how much energy to each coulomb of charge passing through the battery? 1.5 J
POTENTIAL DIFFERENCE OR VOLTAGE (V) A battery with a p.d. of 6V will give how much energy to each coulomb of charge passing through the battery? 6 J
VOLTAGE OR P.D. Voltage (or p.d.) is measured in volts and is given the symbol V
WHAT IS ELECTRIC CURRENT? movement of charge round a circuit. We call this electric current.
ELECTRIC CURRENT: FLOW OF CHARGE t q I    SI Unit; 1 C/s = 1 ampere, A After the French mathematician Andre-Marie Ampere
CHARGE, CURRENT & TIME •If current is charge flowing per second then t Q I  time in seconds (s) Current in Amps (A) Charge transferred in coulombs (C) so a current of 1 A is 1 C of charge transferred in 1 s.
BASIC CIRCUITS • Source • Switch • Conductor wire • Load (Bulb)
Why can a bird sit safely on this high voltage power line? What will happen if the bird spreads its wings and touches the pylon?
SUMMARY OF UNITS Quantity Symbol Units Symbol charge Q coulombs C time t seconds s current I amperes A voltage V volts V
Magnets in Electricity
A magnetic field is the region around a magnet in which a magnetic force can be detected.
A moving charge (electric current) produces magnetic field Hans Christian Oersted
IT CAME FROM… • Moving/ spinning electron. • It is due to the distortion in the electric field caused by the motion (Einstein, 1905, Theory of special relativity). • Every moving/spinning electron is a tiny magnet.
WE CALL IT ELECTROMAGNET • When magnetic field is produced in the current- carrying wire.
APPLICATIONS ARE…
THANK YOU I can do all things through Christ which strengthen me. Philippians 4:13 To God be the Glory
REFERENCES • Murphy & Smooth, (1998). Physics principles and problems, Toronto, Canada: Charles E. Merill Publishing Co. • Eby & Horton, (1986). Physical science, New York: Macmillan Publishing Company • Jones & Childers, (1992). Contemporary college physics, 2ndEd, California: Addison-Wesley Publishing Company • Paul Hewitt, (1998). Conceptual physics, CA: Saunders Publishing