Which of the following describes a calibration method for the magnetometer?

• A. Hold the piece above head level and walk through
• B. Put the calibrating piece in your pocket and walk through
• C. Hold the piece below waist level and walk through
• D. Place the calibrating piece on the floor and walk through

Answer: (B)

The main idea is that calibration must reflect how the device is actually used. For a walk‑through magnetometer, you want the calibrating piece to be in a position that mimics a person carrying it, so the detector experiences a similar magnetic field and shielding as during real use. Putting the calibrating piece in your pocket places it close to your body, producing readings that account for the body’s magnetic influence and the device’s orientation when someone walks through. Placing the piece above head level, below the waist, or on the floor would create readings that don’t match real-world conditions, leading to inaccurate calibration. Carrying it in the pocket thus provides a realistic baseline for proper operation.