Magnets & Motors

Students should complete Parts I–III of Lab 5 (poles, fields, superposition); Part IV (quantitative measurement) is a stretch goal and can be skipped without loss. In Lab 6, prioritize Part I (coil magnetic field vs. current) and Part II (motor analysis); Part III is again optional time-permitting work.

Watch for students disassembling the motor kit in Lab 6 — they sometimes confuse the motor's internal coil with the separate measurement coil. Including a photo of the intended coil in the handout helps.

For magnetic field measurement, students choose between a Logger Pro sensor and a phone app (Physics Toolbox or Phyphox). Let them try both briefly before committing. Remind them to locate the magnetometer sensor in their phone and to use weak magnets when first orienting with the app.

The Millikan scientific integrity discussion in Lab 5 works best as a brief instructor-led conversation (~10 min) rather than a lecture. Frame it around the idea that even excellent scientists need community strategies to protect objectivity, then have students write their own concrete bias-mitigation plans.

For Lab 6's research question critique, display sample questions and have the class evaluate them against the five criteria before students revise their own. Providing both good and flawed examples is more effective than abstract discussion of criteria.

A Desmos graphing template with uncertainty bars and multi-option trendlines is available and works well for students unfamiliar with graphing software

This two-week sequence falls in weeks 5–6 of a 10-week introductory algebra-based physics lab course (BPHYS 118/122) focused on electricity and magnetism. Students should have prior experience with circuits (Labs 1–3) and electrostatics (Lab 4), giving them familiarity with electric charges and fields so they can compare and contrast with magnetic phenomena. Students should also have practiced basic measurement techniques and uncertainty estimation in earlier labs.

The sequence serves a pivotal transitional role in the course. It introduces the final major physics content (magnetism and motors) while simultaneously preparing students for the independent investigation that occupies the remaining weeks. Lab 5 introduces scientific integrity practices that students carry forward, and Lab 6's research question critique directly feeds into students proposing and refining their own research questions for Labs 7–8, culminating in a final presentation in Lab 9.