Explain the principle of working of lvdt

If a digital optical encoder has 7 tracks, then the minimum angular motion that can be measured by this device

The optical encoder is a transducer commonly used for measuring rotational motion.

6. 
   Explain in brief two applications of “Reed switch
   

Reed switches are a special kind of electrical switch, actuated (turned on and off or change over) by magnetism. When a magnetic field is brought close enough to the outer casing of the reed switch, the contacts inside are pushed together or apart. This makes or breaks the circuit, depending on the direction of movement. 

7. 
   Explain the principle of working of Hall effect sensor.
   

Answer: Hall-effect sensors are the linear transducers that are used to measure the magnitude of the magnetic field. Some electrons get collected on one side while some on another side. Due to this, one of the conductor’s plane behaves as negatively charged while the other behaves as positively charged. This creates potential difference and voltage is generated. This voltage is called the Hall voltage.

8. 
   PVDF piezoelectric polyvinylidene fluoride is used in the manufacture of sensor.
   

The signal acquisition experiment of the wrist motion has been carried out by using this sensor. The experiment results show that, with the advantages of small size, good flexibility, and high sensitivity, this wrist PVDF sensor can be used to detect the wrist motion signals with weak amplitude, low frequency, strong interference, and randomness. sensor based on polyvinylidene fluoride (PVDF) piezoelectric thin film was designed and fabricated to detect wrist motion signals. A series of dynamic experiments have been carried out, including the contrast experiments of different materials and force-charge signal characterization. The experimental results show that when the excitation signal exceeds 15 Hz, the sensitivity of the sensor is always stable at 3.10 pC/N.

9.