{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

p240_ct25_f07

# p240_ct25_f07 - Physics 240 Fall 2007 Lecture#25 Median of...

This preview shows pages 1–9. Sign up to view the full content.

Physics 240 Fall 2007 Lecture #25 Dr. Dave Winn 2405 Randall Lab Median of 26/40 on midterm 3, Good job.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Maxwell equations in empty space What happens if you write down Maxwell’s equations to describe electric and magnetic fields far from any charges or currents? Now the parallel of E and B is very clear dt d s d B dt d s d E A d B A d E E B Φ = Φ = = = 0 0 0 0 εμ r r r r r r r r Changing E makes B, changing B makes E….
See Diagram on Board The magnetic field at point P is getting: A) Larger B) Smaller C) No Change

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Follow-up A square contour is drawn centered on point P and perpendicular to the blackboard. The magnetic flux through the contour is: A) Getting bigger B) Getting weaker C) Staying the same.
More Board Diagrams Which of the diagrams could represent the electric field strength along the sides of the contour? A) B)

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Self replicating fields A changing magnetic field produces an electric field (Faraday) A changing electric field produces a magnetic field (Maxwell) Changing B => changing E => changing B => changing E …. .looks like a traveling wave!
EM wave equations An EM wave traveling in the +x direction could be described by these equations “k” is called the wave number ω ” is the familiar angular frequency ω /k = λ f = c f = 1/ Γ = 1/Period ( ) () Γ = = = = = = π πω λ ω 2 2 2 cos cos 0 0 0 0 f k c B E t kx B B t kx E E z y

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
A planar electromagnetic wave is propagating through space. Its electric field vector is given by B = B 0 cos( kz - ω t ) x Its magnetic field vector is: 1: E = E 0 cos( kz - t ) x 2: E = E 0 cos( ky - t ) z 3: E = E 0 cos( kz - t ) y 4: E = - E 0 cos( kz - t ) y Wave travels in z direction = ExB
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 27

p240_ct25_f07 - Physics 240 Fall 2007 Lecture#25 Median of...

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online