Electricity and Magnetism  Electric forces hold atoms and molecules together.  Electricity controls our thinking, feeling, muscles and metabolic processes.

Slides:



Advertisements
Similar presentations
Electric Charge & Electric Field
Advertisements

Electric Forces and Fields
Atoms are composed of Electrons – fundamental negatively charged (-) particle of matter (-1.6 x10-19C) 2. Protons – fundamental positively charged (+)
MUATAN dan MEDAN LISTRIK
Chapter 23 Electric Fields.
Static Electricity Hopefully you studied this link:
Electric Charges and Electric Fields
Electric Forces and Electric Fields
Electric Forces and Electric Fields. Properties of Electric Charges Two types of charges exist They are called positive and negative Named by Benjamin.
CHAPTER 23 : ELECTRIC FIELDS
Chapter 21, Electric Charge, and electric Field. Charles Allison © Electric Charge, q or Q Charge comes in two types 1e = 1.6x Coulombs.
Ch 16: Electric Charge and Electric Field “Opposites attract” by Paula Abdul.
Electricity Click this link Lightning Stepped Leader: Path of ionized air. –large number of quick jumps, each up to 50 meters long. –branch into a number.
Electric Charge, Force, and Field
ELECTROSTATICS: The study of the behavior of stationary charges
Chapter 23 Electric Fields Summer 1996, Near the University of Arizona.
1/10/ Lecture 31 PHY 184 Spring 2007 Lecture 3 Title: The Coulomb Force.
Chapter 23 Electric Charge and Electric Fields What is a field? Why have them? What causes fields? Field TypeCaused By gravitymass electriccharge magneticmoving.
Chapter 21 Electric Charge and Electric Fields
Lecture 2 Properties of Electric Charges Insulators and Conductors Coulomb’s Law Electric Field Problem Solving Strategy.
Chapter 19 Electrostatics Electrostatics A Bit of History Ancient Greeks Ancient Greeks Observed electric and magnetic phenomena as early as 700 BCObserved.
Electrostatics Properties of Electric Charges.
Chapter 23, part I 1. Electrical charge. 2. Coulomb’s Law about force between two point charges. 3. Application of Coulomb’s Law.
Chapter 16 Electric Forces and Electric Fields
Copyright © 2009 Pearson Education, Inc. Lecture 4 – Electricity & Magnetism (Electrostatics) a. Electric Charge, Electric Field & Gauss’ Law.
Electric Charge and Electric Field 16
Introduction to Electrostatics Unit 14, Presentation 1.
Electric Forces and Electric Fields
Electric Forces and Electric Fields
Electric Forces and Electric Fields. Properties of Electric Charges Two types of charges exist Two types of charges exist They are called positive and.
Electricity Charge and Field Presentation 2003 R. McDermott.
Chapter 19 Electric Forces and Electric Fields Electric Charges There are two kinds of electric charges Called positive and negative Negative.
Physics for Bioscience (Part II) Electricity Magnetism Waves Sound Optics by Dr. Chittakorn polyon Department of Physics, Faculty of Science,
Electrostatics Unit 11. Electric Charge Symbol: q Unit: Coulomb (C) Two kinds of Charge: Positive Negative Law of Electrostatics: Like charges REPEL-
What Do All These Pictures Have In Common?
Electric Forces and Fields: Coulomb’s Law
Electric Forces and Fields Chapter 17. Section 17-1 Objectives Understand the basic properties of electric charge Understand the basic properties of electric.
Electric Charge and Electric Field
Electric Force One of the four fundamental forces Responsible for much of our technology Governs chemistry which deals with interactions of the outer electrons.
1 Norah Ali Al-moneef king Saud unversity 23.1 Properties of Electric Charges 23.2 Charging Objects By Induction 23.3 Coulomb’s Law 23.4 The Electric Field.
Electricity and Magnetism  Electric forces hold atoms and molecules together.  Electricity controls our thinking, feeling, muscles and metabolic processes.
Electric Fields and Forces AP Physics B. Electric Charge “Charge” is a property of subatomic particles. Facts about charge:
Electric Field Physics Overview Properties of Electric Charges Charging Objects by Induction Coulomb’s Law The Electric Field Electric Field Lines.
Static Electricity Chapter 16 and 24. Review: The 4 Fundamental Forces Strong Force – The force that is involved in holding the nucleus of an atom together.
Physics 213 General Physics Lecture 1. Today Syllabus Administrative details Class Overview Introduction to Electricity and Magnetism Static electric.
S-113 Define these terms A.Charge B.Potential Difference (Voltage) C.Current (Amps) D.Resistance.
Electric Forces and Electric Fields
Properties of Electric Charges Glass on silk (+ve), plastic on wool (-ve) when rubbed together produce a static electric charge. Benjamin Franklin demonstrated.
Electric Charge and Electric Field
Physics 213 General Physics
Electric Charge (1) Evidence for electric charges is everywhere, e.g.
Electric Charge and Electric Force. Matter is made up of atoms. Atoms are made up of  Electrons  Protons  Neutrons.
Chapter 15 Electric Forces and Electric Fields. First Observations – Greeks Observed electric and magnetic phenomena as early as 700 BC Found that amber,
Chapter 16 Electric Charge and Electric Field. Units of Chapter 16 Static Electricity; Electric Charge and Its Conservation Electric Charge in the Atom.
Chapter 15 Electric Forces and Electric Fields. A Bit of History Ancient Greeks Ancient Greeks Observed electric and magnetic phenomena as early as 700.
Electric Charge and Force Chapter 17.1 Notes. Electric Charge Electric charge is an electrical property of matter An object can have a negative charge,
Bell Ringer Using only the PVC, move the soda can, but you cannot touch the can with the PVC or blow on the can. Explain how you did it.
Electric Forces and Electric Fields. AP PHYSICS B - Chapter 18.
There are only two charges, positive and negative.
Electric Forces and Electric Fields
Electric Forces and Electric Fields
Electric Forces and Electric Fields
Electric Charge, Force and Field
Properties of Electric Charge
Electrostatics Electric charges at rest (static electricity)
Chapter 16 Electric Forces and Fields
Chapter 23: Electric Field
Chapter 7: Electric Field
Electric Charge.
Presentation transcript:

Electricity and Magnetism  Electric forces hold atoms and molecules together.  Electricity controls our thinking, feeling, muscles and metabolic processes.  Electricity and magnetism underpin much of our current technology (e.g. computers).  Electricity and magnetism are linked on a fundamental level.

Electric Charges Evidence for electric charges is everywhere, e.g. –static electricity. –lightning. Objects may become charged by contact and frictional forces. Benjamin Franklin (1700’s) discovered that there are two types of charges: –positive charge. –negative charge. Franklin also discovered that like charges repel and unlike charges attract one another. Electric charge is –quantized (Millikan) –conserved (Franklin)

Electric Charges in Atoms Atoms consist of a nucleus containing positively charged protons. The nucleus of an atom is surrounded by an equal number of negatively charged electrons. The net charge on an atom is zero. An atom may gain or lose electrons, becoming an ion with a net negative or positive charge. Polar molecules have zero net charge but their charges are unevenly distributed in space (e.g. water). Nuclear diameter ~ m (femtometer) Atomic diameter ~ m (nanometer)

Classes of Materials CONDUCTORS are materials in which charges may move freely (e.g. copper). INSULATORS are materials in which charges cannot move freely (e.g. glass). SEMICONDUCTORS are materials in which charges may move under some conditions (e.g. silicon).

Charges and the Earth The earth acts as a near-infinite source or sink of charges, and therefore its net charge cannot easily be changed. Any conductor in contact with the earth is said to be GROUNDED and cannot receive a net charge. (principle of lightning rod)

Induced Charge Charged objects brought close to a conductor may cause charge to redistribute (polarize the conductor). If a polarized conductor is momentarily grounded, charge will be transferred to/from the earth, and it may be left with a net charge (by INDUCTION). Objects may be charged by –conduction (requires contact with another charged object. –induction (requires no contact with another charged object).

Electric Force and Coulomb’s Law If two point charges q 1 and q 2 are separated by a distance r, the magnitude of the electric force F e between them is: where k = 8.99 x 10 9 N  m 2 /C 2 is the Coulomb constant, q 1 and q 2 are in Coulombs ( C ), r is in meters ( m ) and F e is in Newtons ( N ).

Quantum of Electric Charge Electric charge is quantized. The smallest possible unit is the charge on one electron or one proton:  e  = x Coulombs No smaller charge has ever been detected in an experiment.

Electric Force Vector The force on a point charge q 1 exerted by another point charge q 2 separated by a distance r 21 is:

Principle of Superposition For a system of N charges q 1, q 2, q 3, …, q N, the resultant force F 1 on q 1 exerted by charges q 2, q 3, …, q N is: Each charge may be considered to exert a force on q 1 that is independent of the other charges present.

Field Forces and Electric Field Field forces act through space even if there is no contact (e.g. gravitational force). The ELECTRIC FIELD E is defined in terms of the electric force that would act on a positive test charge q 0 :

Electric Field The electric force on a positive test charge q 0 at a distance r from a single charge q : The electric field at a distance r from a single charge q:

Electric Field due to a Group of Charges:

Example Problem Four point charges are at the corners of a square of side a as shown. a)Determine the magnitude and direction of the electric field at the location of q. b)What is the resultant force on q? 2q q 4q3q a a a a

Electric Field from Continuous Charge Distributions If a total charge Q is distributed continuously, it may be sub-divided into elemental charges dQ, each producing an electric field dE : ε 0 = permittivity of free space

Uniform Charge Distributions Volume Charge Density: ρ=Q/V Surface Charge Density: σ=Q/A Linear Charge Density: λ=Q/l Example: A continuous line of charge lies along the x- axis, extending from x=x 0 to positive infinity. The line carries a uniform linear charge density λ 0. What are the magnitude and direction of the electric field at the origin?

Example Problem: Electric Field due to a Power Line A power line is suspended a constant distance y o above the ground, and carries a uniform linear charge density λ o. Assume that the wire is infinitely long and that the ground is a flat plane. What are the magnitude and direction of the electric field on the ground immediately below the power line?

Electric Field Lines Electric Field Lines: describe the direction of the electric field at any point The density of field lines is proportional to the magnitude of the electric field. The directions of arrows indicate the direction of the force on a positive test charge. Rules: –Lines begin on + charge and end on – charge –Number of lines approaching or leaving a charge is proportional to the magnitude of the charge. –Electric field lines may never cross.

Electric Field Lines: Conventions Positive Point Charge Negative Point Charge

Electric Field lines