Answer:
1. A switch is a component which controls the open-ness or closed-ness of an electric circuit. ... In the on state, a switch acts just like a piece of perfectly-conducting wire. A short. This closes the circuit, turning the system "on" and allowing current to flow unimpeded through the rest of the system.
2. SPST and DPST
SPST: Tilt switches contain a conductive liquid and when tilted this bridges the contacts inside, closing the switch. They can be used as a sensor to detect the position of an object
DPST: A DPST switch turns two circuits on or off. A DPST switch has four terminals: two inputs and two outputs. The most common use for a DPST switch is to control a 240-volt appliance, where both supply lines must be switched, while the neutral wire may be permanently connected.
3. The pepper grinder was invented by Peugeot of France in 1842. Earlier versions of pepper mills were based on a mortar and pestle design. The pepper grinder allowed for a less labor intensive way to crack the peppercorns. Hanging upside down can be a fun activity. It may even make you feel like a kid again, especially if you try it out on the monkey bars. But some adults today are practicing hanging upside down for another reason.
As for the forth one, I'm not sure!!
Hope this helps!!
Explanation:
