1. Measure the dark resistance value
The method of measuring the dark resistance value: Cover the photosensitive surface of the photoresistor with a piece of black paper. During the measurement, the pointer of the digital multimeter should remain basically unchanged, and the resistance value is close to infinity. The larger the dark resistance value, the better the performance of the photoresistor. Good; if this value is very small or close to zero, it means that the photoresistor has been burnt through and damaged and can no longer be used.
2. Measure the light resistance value
Turn the light-transmitting window of the photoresistor towards the light source. At this time, the pointer of the multimeter should swing by a large margin, and the resistance value will be significantly reduced. The smaller the resistance value, the better the performance of the photoresistor; The performance of the photoresistor is very poor; if the resistance value is infinite, it indicates that the internal open circuit of the photoresistor is damaged, and it can no longer be used.
