Tablet-based magnetic-field demonstration set (coil circuit, ruler, book, MagnetMeter app)¶

Element · All elements
Evidence · 4 claims (3 for, 1 against) · 1 study (1 design), q2 · 1 of 1 report an effect size · 4 claims rest on one study

Description¶

A low-cost experimental kit for physics demonstrations in which a tablet's magnetometer measures the magnetic field of a current-carrying coil or a magnet. The article states "The demonstration set used is composed by an electrical circuit, a ruler and a book", with the circuit built from a wirewound potentiometer (up to 30Ω), a 10Ω resistor, a cell-phone electrical source, a digital multimeter and a coil of N = 62 turns. Before each run the MagnetMeter app is zeroed to set aside interferences such as the Earth's magnetic field.

Design Implications¶

Context¶

Requirements¶

• A tablet or phone with a magnetometer running a magnetometer app (MagnetMeter for iPad; a similar app suggested for Android), plus the coil circuit components connected in series.

Constraints¶

• The distance to the magnetic sensor inside the iPad must be added to the ruler-measured distance; the extra 10Ω resistance may be needed to avoid high currents for safety.

Target Learners¶

• physics students in science education settings

Target Learning Goals¶

• understanding dependencies of the magnetic field of a coil (on current and axial distance) and estimating air permeability

Claims¶

• Magnetic field falls off as the inverse cube of axial distance for both a coil and a magnet [+W]
• Magnetic field measured by a tablet magnetometer depends linearly on the coil current [+W]
• The demonstration set yields a fair estimate of air permeability µair from coil data [+W]
• The magnet data cannot determine air permeability; only the magnet's dipole moment can be estimated [-W]

Related Elements¶

Examples¶

• Extend tablet magnetometer experiments to other current geometries

Key Sources¶

• V.O.M. Lara, D. F. Amaral, D. Faria, and L. P. Vieira. (2014). Demonstrations of magnetic phenomena: Measuring the air permeablity using tablets. https://arxiv.org/abs/1405.6581