Search coil by computer to determine displacement in multiple dimensions. Additionally, a second search coil can be added to measure torsional rotation. A more crude search coil also called exploring coil is also used in laboratory experiments in schools to measure the magnetic field in a certain region of space. In this case the search coil consists of a simple wire coil or solenoid connected to a sensitive ammeter or galvanometer. The coil is placed in the magnetic field to be measured and quickly withdrawn to a region of space with a negligible magnetic field. As the search coil moves the magnetic
Helmholtz coil field and living tissue). The required magnetic fields are usually either pulse or continuous sinewave. The magnetic field frequency range can be anywhere from near DC (0 Hz) to many kilohertz or even megahertz (MHz). An AC Helmholtz coil driver is needed to generate the required time-varying magnetic field. The waveform amplifier driver must be able to output high AC current to produce the magnetic field. Use the above equation in the mathematics section to calculate the coil current for a desired magnetic field, . formula_25 where formula_15 is the permeability of free space or formula_18 formula_19 = coil current,