Ammeter permanent magnet causes the coil to move. The modern form of this instrument was developed by Edward Weston, and uses two spiral springs to provide the restoring force. The uniform air gap between the iron core and the permanent magnet poles make the deflection of the meter linearly proportional to current. These meters have linear scales. Basic meter movements can have full-scale deflection for currents from about 25 microamperes to 10 milliamperes. Because the magnetic field is polarised, the meter needle acts in opposite directions for each direction of current. A DC ammeter is thus sensitive to which way round
Becky Measures Becky Measures Becky Measures (born 13 October 1981 in Derbyshire, England), from Bakewell, Derbyshire, is a radio presenter on Peak FM, an independent local radio station in Derbyshire and a professional charity fund-raiser. She held a variety of jobs including being an extra for the locally filmed television series "Peak Practice" before moving into radio. In 2004, Measures, then 23, decided to have a double mastectomy after a genetic test revealed that she had an 80 to 90 per cent risk of developing breast cancer. Both her mother and a cousin, Helen, had suffered from the same illness. To help