malusLaw - I nverse Square Law and Pola rization of L ight...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Inverse Square Law and Polarization of Light Lab Reading Assignment: Chapter 33.3-33.7. Introduction Electromagnetic waves consist of oscillating electric and magnetic fields with the following characteristics: o E and B are perpendicular to each other; o E and B are in phase; o E × B gives the direction of propagation of the wave; o | E | = c | B | , where c is the speed of light. o The rate of energy transport per unit area is given by the Poynting vector: . o The time-averaged value of the Poynting vector is known as the intensity I and is given by: , where E m is the amplitude of the electric field. The Inverse Square Law: electromagnetic radiation from a point source spreads out isotropically in all directions. The intensity of the radiation at any given distance, r , from a source of power output P s is given by: Polarization of electromagnetic waves: o The plane defined by the axis of propagation of an electromagnetic wave and the direction of the electric field is called the “plane of polarization” (see Fig. 1);
Background image of page 1

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

View Full DocumentRight Arrow Icon
o A “plane polarized” wave or, equivalently, a “linearly polarized” wave is one whose plane of polarization does not change with time. o The light emitted from most common sources is “unpolarized.” In this case, the plane of polarization changes randomly with time, Polarizers and analyzers : when unpolarized light is transmitted through certain materials (e.g. “polaroid sheets” -- invented by E. H. Land in 1938), the transmitted light has half the intensity of the incident light and is linearly polarized parallel to a special axis. If a second identical sheet, or “analyzer,” is
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 8

malusLaw - I nverse Square Law and Pola rization of L ight...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online