Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Newton's Rings and Central Fringe
Name: Rakshit
Status: student
Age: N/A
Location: N/A
Country: N/A
Date: N/A


Question:
Why the central fringe appears to be light rather than dark in formations of Newton's Rings?



Replies:
Dark only happens if waves cancel. Waves only cancel if they have different phases such as 0 and 180 degrees, or 0, 120, and 240 degrees, or a similar balanced set. Newton's rings are diffraction around a circular object. It is circularly symmetric at the center-point, so all paths to that point will have equal distance and phase. All will be 0 degrees relative to each other. So they must add constructively instead of canceling. Hence a bright spot.

Jim Swenson



Click here to return to the Physics Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory