It is frightening, and even dangerous, to come back to a dark house at the end of a working day. There are many different types of outdoor lights on the market. Emily wants the outdoor lights at her home to be on in the evenings when she comes from work. She does not want to leave the lights on all day as this will be a waste of electricity and unnecessarily expensive. She needs some type of device that detects the fading daylight. This will cause her outside house lights to switch on automatically once the correct level of darkness has been reached.
motivate what kind of system is needed?