CDs reproduce 44,100 samples per second. Which has a maximum frequency reproduction of 22,050 Hz, or just a hair past the upper limit of human hearing. In this way CDs can theoretically reproduce any frequency in the human hearing range.
3. Which motor is NOT suitable for use as a DC machine?
The flyback is usually connected to the system that pulls the electron beam across the screen in one direction to 'paint' a line of the image and then returns in the other direction much faster.
Neon lighting runs at a high voltage, typically above 1000 Volts. A fireman's switch protects a fireman from receiving a shock when a water jet is sprayed onto the installation. The switches are red, and mounted in a conspicuous position. (This is specified by IEE Regulations (Europe), SANS (South Africa), UK Electricity regulations and many Asian countries. I am unable to confirm other countries' requirements, so feel free to let me know.)