This research aims to develop a wireless magnetic field sensor named "K-Mag Tracer" as an innovative teaching tool for physics laboratory courses. The system utilizes a linear Hall effect sensor integrated with a microcontroller board. The device is designed for real-time data display through two channels: an onboard OLED screen and a web browser on mobile devices. Additionally, an online lesson system was developed to support self-directed learning in magnetic phenomena.

The results show that the K-Mag Tracer is capable of measuring magnetic fields within a range of +/-120 mT. Users can choose between two data logging modes:

• Time-based
• Event-based

Performance comparison against two standard commercial sensors demonstrated consistent measurements with an error of less than 2%, which falls within the acceptable standard for physics laboratories. Consequently, this innovation serves as an effective tool to promote active learning and facilitate physics data analysis in the digital era.