Application "Metal Detector HD" uses built-in magnetic sensor. With the use of magnetometer it measures electromagnetic field (EMF) value in your surrounding.
Actual value of the field is displayed as microtesla. Induction of Earth's magnetic field ranges from 30 to 60 microtesla (µT). If the intensity increases above 60 µT it may mean that the telephone is near to ferromagnetic materials (metallic objects). You can try to find wires in the walls and metallic objects under the ground or simply prank your friends that your phone is able to detect presence of a ghost ;)
Beside presenting actual µT value, this tool displays the chart with the measurements of the last 15 seconds and presents minimum and maximum magnetic field strength. You can reset those readings any time.
Remember that this tool uses built-in magnetic field sensor. Not all phones are equipped in such a sensor. Please check it in your phone specification.
Accuracy of measurements can be disturbed by electronic devices, such as TV set or a PC screen. It's better not to use this application around such devices. Additionally some phone cases may have metallic parts. Before using the application you should remove such parts.
Before working with metal detector it should be calibrated. To do it, start an application, raise the telephone high and "draw" number 8 pattern in the air. Now you can start playing with the detector.
Our app can only detect ferromagnetic metals. It will not detect gold, silver or copper coins. They are classified as non-ferrous that has no magnetic field.