Context and question: Mechanically controlled variable capacitors allow the plate spacing to be adjusted, for example by rotating or sliding a set of movable plates into alignment with a set of stationary plates. Low cost variable capacitors squeeze together alternating layers of aluminum and plastic with a screw. Electrical control of capacitance is achievable with varactors (or varicaps), which are reverse-biased semiconductor diodes whose depletion region width varies with applied voltage. They are used in phase-locked loops, amongst other applications.
How do cheap variable capacitors vary the separation distance between layers of a plastic and aluminum?
Answer: with a screw
Context and question: A freight elevator, or goods lift, is an elevator designed to carry goods, rather than passengers. Freight elevators are generally required to display a written notice in the car that the use by passengers is prohibited (though not necessarily illegal), though certain freight elevators allow dual use through the use of an inconspicuous riser. In order for an elevator to be legal to carry passengers in some jurisdictions it must have a solid inner door. Freight elevators are typically larger and capable of carrying heavier loads than a passenger elevator, generally from 2,300 to 4,500 kg. Freight elevators may have manually operated doors, and often have rugged interior finishes to prevent damage while loading and unloading. Although hydraulic freight elevators exist, electric elevators are more energy efficient for the work of freight lifting.[citation needed]
What type of notice is required to be visible in most freight elevators?
Answer: a written notice in the car that the use by passengers is prohibited
Context and question: Conflict with Arius and Arianism as well as successive Roman emperors shaped Athanasius's career. In 325, at the age of 27, Athanasius began his leading role against the Arians as his bishop's assistant during the First Council of Nicaea. Roman emperor Constantine the Great had convened the council in MayAugust 325 to address the Arian position that the Son of God, Jesus of Nazareth, is of a distinct substance from the Father. Three years after that council, Athanasius succeeded his mentor as archbishop of Alexandria. In addition to the conflict with the Arians (including powerful and influential Arian churchmen led by Eusebius of Nicomedia), he struggled against the Emperors Constantine, Constantius II, Julian the Apostate and Valens. He was known as "Athanasius Contra Mundum" (Latin for Athanasius Against the World).
How many years did the First Council of Nicaea last?
Answer:
unanswerable