1. Check the strength of the electromagnetic waves in a living enviroment or around a transmitter. (You can use the tester to check PC, radio, mobile phone, blower, refrigerator, electric oven, electric cooker, computer room. control room, signaling tower, duplicating machine,facsimile machine, microwave oven, air conditioner, and etc.) 2. Help the patients with medical implants and pregnant women to avoid strong electromagnetic waves. 3. Remind the persons who work near a transmitter to take preventive measure. 4. Check the strength of electromagnetic waves around the device being interfered with by electromagnetic waves. 5. Help find a seat where the strength of the electromagnetic waves caused by electrical machine or transformer is low and neglectable when you take a high speed train or other vehicles. 6. Check the electromagnetic wave strength in recreation places or other places.