The most difficult electrics riddles

Any lead-acid battery system when overcharged will produce hydrogen gas by electrolysis of water. If the rate of overcharge is small, the vents of each cell allow the dissipation of the gas. A severe overcharge may produce a flammable concentration of hydrogen.

St. Elmo's fire is a form of plasma. The electric field around the object in question causes ionization of the air molecules, producing a faint glow easily visible in low-light conditions. Conditions that can generate St. Elmo's fire are present during thunderstorms, when high voltage differentials are present between clouds and the ground underneath. The nitrogen and oxygen in the Earth's atmosphere cause St. Elmo's fire to fluoresce with blue or violet light; this is similar to the mechanism that causes neon lights to glow

Leyden jar is a device that stores static electricity between two electrodes on the inside and outside of a glass jar. It was the first known form of a capacitor (condenser). The glass plays the role of a dielectric material.

According to Ohm's law, the resistance (R) of an object is defined as the ratio of voltage across it (V) to current through it (I) : R = V/I. R = 12/4 = 3.

An AAA battery is a standard size of dry cell battery commonly used in low-drain portable electronic devices, such as TV remote controls, MP3 players and digital cameras.