Course Organization

What you need to remember from 303K Vectors Right Hand Rule

Clicker Question 1 Choice A2 B C32 D3

Clicker Question 2 Choice A B C4 A B C

Clicker Question 3 Choice A B C4 Unit vector A B C

aurora borealis Sun spits out Charged Particles (Solar Wind) Earth’s Magnetic Field extends out into space and collects charged solar wind. Charged particles are concentrated at poles Collisions of these high velocity charges with air makes the light of the aurora What will you learn? Interaction of Matter and Electromagnetic Fields Backpacking in Alaska

The interactions between Matter and Electric and Magnetic fields can be explained with just a few equations. Maxwell equations: Lorentz force: More Mathematically …

Two types: positive and negative Like charges: repel Opposite charges: attract Charge is quantized in units of e Millikan’s oil drop experiment ( ) Point charge: Size is small compared to the distance between it and other objects of interest Electric charge is an intrinsic property of the fundamental particles that everything is made of Point Charges

Q1Q1 Q2Q2 F F "The magnitude of the electrostatic force between two point charges is directly proportional to the magnitudes of each charge and inversely proportional to the square of the distance between the charges." The Coulomb Force Law Charles-Augustin de Coulomb ( )

The Coulomb Force Law  0 = permittivity constant Force repulsive r F 21 Force attractive r F 21 1 Force on “2” by “1”

Units and Constants SI units of electric charge : Coulomb, C Constants : 1/4  0 = 9x10 9 N. m 2 /C 2  0 = 8.85x C 2 /N. m 2 permittivity constant e = 1.602x C 1 C = 6.24x10 18 elementary charges ParticleCharge electron-e positron+e proton+e antiproton-e muon+e or –e pion +e or –e or 0 neutron0

Structure of Atom Nucleus: ~10 4 times smaller than electron cloud, ~10 4 times heavier than electron. Matter consists of atoms 1 cm 3 : ~10 24 atoms Example: nucleus of the iron atom Size: ~10 –15 m, mass: ~ kg 1Å= m Nucleus charge = +Ze, atom with Z electrons is neutral.

The Concept of Electric Field Accelerates at 9.8 m/s 2 – why? Accelerates at m/s 2 – why? There are many possible configurations of charges to produce the observed effect.

There is something in space waiting for a charged particle to interact with it! This virtual force is called electric field. An electric field created by charge is present throughout space at all times, whether or not there is another charge around to feel its effect. Electric Field

The Electric field of the Point Charge Q Force between Charges Q q Electrical Field is convenient tool turns out to be measurable … so really exists + +

Electric Field of Point Charge + Spherically Symmetric +

Draw the E field for a Negative Charge _ _

E Field Lines Direction of Electric Field Points along Line Field Lines Isolated Positive Charge Isolated Negative Charge + _ + + Begin and End on Charges or Infinity; Never Cross

Draw the Electric Field Lines for 2 negative particles _ _

The E of a Uniformly Charged Spherical Shell for r>R (outside) for r<R (inside) Recall this every night before bed! What does E look like very far away?

Things to do _ Homework on Quest: Due 9/2 Read Ch i-Clickers (register on Quest)