Interview Protocol

Abstract

1. Warm­up subject. Get background and experience. 2. Pose two driving questions. • Could a magnet affect an electric current? How or why? • What are some of the ways that you could make a magnet? II. Sim 1. Play with sim (either VM or NM) • Think out loud. • Allow up to 45 minutes of uninterrupted exploration. 2. After exploration, pose this question: In all the cases shown in the sim, there is one principle (called Faraday's Law) that describes what makes the light bulb turn on. Try to state this principle as generally (and as simply) as possible. Make sure your statement works for the "Pickup Coil", the "Transformer" and the "Generator". 3. Rank difficulty of learning Faraday's Law from 1­5. III. Flux Lesson 1. Explain: "Now I'd like to work through a concept that we use in physics called flux. Flux describes the rate (speed) of flow through a given area." 2. Work through the following steps verbally, assisting student along the way to learn flux. • Think of a room fan blowing air. Draw the fan and the air flow around it. Where is the air moving fast and slow? What direction is the flow at various points? • Think of a windsock (the sock part is not as important as the hoop part). If "flux" is a measure of how much flow there is through the hoop, how does the flux compare when the following variables are changed: flow speed, loop area, loop orientation. 3. Referring to a vector field drawing (the student's own, if it's good enough), pose the questions about the factors that determine flux. Correct answers and explain where necessary. 4. Rank difficulty of learning the meaning of flux from 1­5. IV. Follow­up Activity 1. Look again at both driving questions. 2. Further questions: • Have you ever heard of a "magnetic field"? Describe your impression of a magnetic field and draw a picture of it. • What are the differences and similarities between a bar magnet and an electromagnet?