In a gun-type bomb, Uranium-235 is the fuel. In an implosion bomb, Plutonium-239 is the fuel. A fusion-boosted atomic bomb uses the implosion design, with the addition of gaseous tritium (Hydrogen-3). Producing the appropriate amounts of fuel for bombs is expensive, time-consuming, and difficult.
What does an inhibitor switch do? An inhibitor switch basically tells your vehicle whether its in motion or in park. It can tell the car to park or to go into first gear etc.
Oil pressure switches are typically used as an actuator which directly activates the oil warning light in driver dashboard when the oil pressure in the engine will fall below the preset critical level or brings a signal to the ECU (engine control unit), so to be warned about low pressure of engine oil and prevent damage to the engine.