<Dl> <Dd> β = tan ⁡ (θ). (\ displaystyle \ beta = \ tan (\ theta).) </Dd> </Dl> <Dd> β = tan ⁡ (θ). (\ displaystyle \ beta = \ tan (\ theta).) </Dd> <P> Hall probes are often used as magnetometers, i.e. to measure magnetic fields, or inspect materials (such as tubing or pipelines) using the principles of magnetic flux leakage . </P> <P> Hall effect devices produce a very low signal level and thus require amplification . While suitable for laboratory instruments, the vacuum tube amplifiers available in the first half of the 20th century were too expensive, power consuming, and unreliable for everyday applications . It was only with the development of the low cost integrated circuit that the Hall effect sensor became suitable for mass application . Many devices now sold as Hall effect sensors in fact contain both the sensor as described above plus a high gain integrated circuit (IC) amplifier in a single package . Recent advances have further added into one package an analog - to - digital converter and I2C (Inter-integrated circuit communication protocol) IC for direct connection to a microcontroller's I / O port . </P>

Which meter is based on the principle of hall effect
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