1. QUESTION:
Illustrated below is a snapshot of the electric field component of an electromagnetic wave as it travels through space. At which of the locations indicated would a charged particle experience the strongest force? A B C D
SCRIPT:
Illustrated here is a snapshot of the electric field component of an electromagnetic wave as it travels through space.
At which of the locations indicated would a charged particle experience the strongest force?
PAUSE
The graph shown here tells us the relative strength of the force that a charged particle would experience at the different locations.
A charged particle would experience the greatest force at the troughs, as in point A, and at the crests.
The correct answer is A.
CLICK
The troughs are the lowest points in the wave.
CALLOUT “Troughs” --- draw arrows pointing to troughs
The crests are the highest points.
CALLOUT “Crests” ---- draw arrows pointing to crests.
At the nodes, where the electric field is zero, as in points B and C,
CLICK CLICK a charged particle will feel no force.
At points between a node and crest,
CLICK as in point D,
CLICK the force that a charged particle will feel increases.
CLICK Then it decreases from the crest to the next node.
CLICK Then increases from the node to the next trough.
CLICK Then decreases from the trough to the next node.
You will note that this pattern just keeps repeating. The distance spanned by one of these repeating patterns is called the wavelength,
The wavelength is usually represented by the greek letter lambda (lower case).
HIGHLIGHT lambda E
distance
, wavelength

2. Video ID: © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Narrator: Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08