Poll 1; ans÷ rectifier In physics, a rectifier is a device that converts alternating current (AC) into direct current (DC). It allows current to flow in one direction while blocking it in the other direction. Poll 2;ans÷photocell A photocell, also known as a photodiode or light-dependent resistor (LDR), is a device that converts light energy into electrical energy. Its main function is to detect light and control the flow of electrical current accordingly. Poll 3; ans ÷seismograph it's use to measure the vigorous shaking of the earth tonic plates during earthquake