LDR-yada iyo thermistors-ka

An LDR is made of a semiconductor, and the brighter the light shining on it, the lower its resistance. Light transfers energy that enables electrons in a semiconductor to move as they do in a metal conductor. A thermistor is made of a semiconductor, and the hotter it is, the lower its resistance. Heating transfers energy that enables electrons in a semiconductor to move as they do in a metal conductor. A potential divider circuit can be set up with an LDR/thermistor to trigger a switch if it becomes too dark or too cold.