This is a circuit in which a motor will turn on and spin when there is adequate light in the ambient environment. As soon as ambient light is sensed by the circuit, the motor will automatically turn on and remain on as long as the light remains.
Light Dependent Resistors (LDR) are also called photoresistors. They are made of high resistance semiconductor material. When light hits the device, the photons give electrons energy. This makes them jump into the conductive band and thereby conduct electricity.
To make an LDR circuit run four motors, you will need an LDR sensor, an Arduino board, motor drivers, and four DC motors. Additionally, you will need jumper wires, a breadboard, and a power source.