ฉันต้องใช้ภาษาอังกฤษถูกหลักไวยากรณ์
Since World War u sensitive magnetometers have been designed around quantum mechanical properties. The proton-precession magnetometer depends on the fact that the nucleus of the hydrogen atom, a proton, has a magnetic moment proportional to the angular momen tum of its spin. Because the angular momentum is quantized, the proton magnetic moment can only have specified values, which are multiples of a fundamental unit called the nuclear magneton. The situation is analogous to the quantization of magnetic moment associated with electron spin, for which the fundamental unit is the Bohr magneton. The ratio of the magnetic moment to the spin angular momentum is called the gyromagnetic ratio(y, of the proton. It is an accurately known fundamental constant with the value 2.675 13 x 105 s-IT-1 The proton-precession magnetometer is simple and robust in design. The sensor of the instrument consists of a flask containing a proton-rich liquid, such as water Around the flask are wound a magnetizing solenoid and a detector coil(Fig. 5.42); some designs use the same solenoid alternately for magnetizing and detection. When the current in the magnetizing solenoid is switched on, it creates a magnetic field of the order of 10 mT, which is about 200 times stronger than the Earth 's field.