A collection of physics problems - probably to be solved outside of class - that incorporate interactive content using Physlets. The problem set is focused on various aspects of Faraday's law of induction.
Type of Material:
Homework, just-in-time exercise, pre-lab exercise
Technical Requirements:
Difficult to run on Macs at present
Identify Major Learning Goals:
Conceptual and analytic familiarity with Faraday's Law.
Target Student Population:
Introductory physics
Prerequisite Knowledge or Skills:
Electromagnetic induction
Content Quality
Rating:
Strengths:
Most problems in this set are focused on elements of this subject area that often present the greatest conceptual challenge to students (eg. 9.7.1 and a2 on the direction of induced current flow according to Lenz's Law). These problems can be relatively easily altered, or used as templates for other similar problems, allowing the instructor to customize an assignment.
Concerns:
In problem 9.7.2, the z-axis points out of the computer screen.
In Problem 9.7.3, there is a minor bug in changing from >> to << or vice versa (after pausing).
Problem 9.7.a2 seems to require an implicit convention that positive voltage produces a clockwise current in the loop as you look at it.
In Problem 9.7.a3 - voltage across R should be labeled RMS.
General Comments on Quality: These problems can be useful to students in developing conceptual understanding of relatively difficult material, but they are limited as written because users cannot change any parameters of the problems.
Potential Effectiveness as a Teaching Tool
Rating:
Strengths:
Recommended Uses: Homework, pre-lab, JITT
In this problem group, physlets are used to animate the chosen circuit situation with some sort of graphical feedback that allows students to determine relevant circuit behaviors. To answer the questions, students must interpret and in most cases analyze this data. Problems such as 9.7.1 may simulate actual laboratory exercises, and would make a very effective pre-lab exercise. Problems such as 9.7.3-4 allow students to visualize circuit parameters such as magnetic flux that are not easily measured directly in the laboratory.
Most of these problems test students' qualitative understanding of material that it is difficult to get across with static pictures.
Concerns:
This is a sample collection; additional problems of this sort will be needed for students to comprehend the concepts involved.
General Comments on Effectiveness: As usual, these physlet-enhanced problems are an improvement over traditional end-of-chapter textbook problems. Problem 9.7.a2 should be remarkably effective in promoting conceptual understanding of Lenz's Law.
Some of these problems are effective as is; for others the effectiveness could be much improved by asking different or additional questions. The lack of user control over any parameter limits exploration of Faraday's law. The following comments are arranged by specific problem:
9.7.1 - The lack of a visual clue about the magnet's motion is disconcerting.
9.7.2 - This problem would be pedagogically more effective if there were a series of several questions guiding students to the most general form (e.g., Does the field on either side change in time? How does the z-component for x>0 compare to that for x <0?) They are unlikely to get the complete solution, otherwise.
9.7.3 - The graph with the evolving time scale is confusing, and distracts from a complete understanding of the change in magnetic flux. Otherwise, a very effective problem.
9.7.ap2 - This is not really a Faraday's law problem. However, the applet could be used to create an interesting, though difficult, Faraday's law problem or lecture/demonstration since the induced voltage in a loop is shown as the loop is dragged around in the vicinity of the straight current-carrying wire.
Ease of Use for Both Students and Faculty
Rating:
Strengths:
Physlets can be relatively easily modified, or adapted to generate a variety of additional problems.
Concerns:
In 9.7.3, there is an odd hysteresis when using the step forward and step backward buttons.
General Comments on Usability: The physlets are simple to use,
with controls behaving as expected.
Creative Commons:
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