Electricity and Magnetism

Magnetic Fields from Electric Currents

One of the classes of problems dealing with magnetic fields concerns the production of a magnetic field by a current-carrying conductor or by moving charges.  It was Oersted who discovered back in the early 1800's that currents produce magnetic effects. The quantitative relationship between the magnetic field strength and the current was later embodied in Ampere's Law, an extension of which made by Maxwell is one of the four basic equations of electromagnetism.

Introduction

In this lesson students will find that a current-carrying loop can be regarded as a dipole, as it generates a magnetic field for points on its axis.  Students use PocketLab Voyager and Phyphox software to compare experiment and theory for the magnetic field on the axis of a current loop.  A similar experiment not making use of Phyphox can be found by clicking this link.  An experiment making use of a magnet, instead of a

Introduction

Magnets, from the traditional alnico bar magnets to the modern neodymium magnets, have been of interest to most everyone for decades. The attraction or repulsion of two such magnets when brought close together is particularly interesting. This can be expressed by making quantitative measurements relating magnetic field strength to distance from the magnet.

A thermoelectric generator (TEG) is a device that converts temperature differences directly into electrical energy.  In the past several years, there has been a great deal of research in the use of TEGs to recover electrical energy from waste heat produced in a variety of systems.  As a result of this research, the study of thermoelectric generators in physics and engineering curricula is well worth including in NGSS-based coursework.

Hello All,

I'm an AP Calculus teacher, and I used the attached lab to introduce position vs. time graphs to my students. My school doesn't offer physics after freshmen year and historically students have struggled to translate graphs into the actual motion that they represent. This year, using PocketLab and some magnets, the students were able to create their own position vs. time graphs, and concept mastery has been significantly higher. I'm definitely planning on repeating this lab next year!

One of the classes of problems dealing with magnetic fields concerns the production of a magnetic field by a current-carrying conductor or by moving charges.  It was Oersted who discovered back in the early 1800's that currents produce magnetic effects. The quantitative relationship between the magnetic field strength and the current was later embodied in Ampere's Law, an extension of which made by Maxwell is one of the four basic equations of electromagnetism.

In this lesson students will find that a current-carrying loop can be regarded as a magnetic dipole, as it generates a magnetic field for points on its axis.  The figure below shows a diagram and the equation for the magnetic field B.  Derivation of this equation requries knowledge of the Biot-Savart Law, calculus and trigonometry.  But in this lesson we are interested only in comparing experimental results from PocketLab's magnetometer to the theoretical equation in the figure below.  More advanced students can consider derivation of the equation, if they wish.

In this lesson students will find that a current-carrying loop can be regarded as a magnetic dipole, as it generates a magnetic field for points on its axis.  The figure below shows a diagram and the equation for the magnetic field B.  Derivation of this equation requries knowledge of the Biot-Savart Law, calculus and trigonometry.  But in this lesson we are interested only in comparing experimental results from PocketLab's magnetometer to the theoretical equation in the figure below.  More advanced students can consider derivation of the equation, if they wish.

These coils come in pairs with the same number of windings of wire on each of the two coils. In "true Helmholtz" configuration: (1) the coils are wired in series with identical currents in the same direction in each coil, and (2) the coils are placed a distance apart that is equal to the radius of each coil. When in this configuration, they produce a very uniform magnetic field that is directed along their common central axis.