1. For other examples, see Forinash, K. and Wisman, R. “Smartphones as portable oscilloscopes for physics labs,” Phys. Teach. 50, 242–243 (April 2012) and “Photogate timing with a smartphone,” Phys. Teach. 53, 234 (April 2015).
2. See, for example, John W. Snider and Joseph Priest, Electronics for Physics Experiments: Using the Apple II Computer/Book with Disk (Addison-Wesley, Reading, 1989).
3. The original app, “Mobile Science–Temperature,” is no longer available from the Apple App Store. Contact the author, Raymond Wisman, regarding implementation questions on using the headphone port for data measurement.
4. A list of sensors and how they function can be found at https://www.sensorland.com. Ready to run external thermometers with software are now commercially available, for example from Weber (https://ogy.de/ambienttemperatureprobe) and Thermodo (http://thermodo.com).