What causes the zap or shock when touching a doorknob?

The zap or shock experienced when touching a doorknob is primarily caused by electrical charges jumping from one object to another. This phenomenon is closely associated with static electricity, which occurs when there is an imbalance of electric charges on the surfaces of materials. When a person walks across a carpet or their clothing rubs against another surface, they can accumulate excess electrons, becoming negatively charged.

Upon touching a doorknob, which is usually made of metal, the excess negative charges can rapidly transfer to the doorknob. The sudden movement of these electrical charges is what causes the brief sensation of a shock. The sensation can be startling, but it is generally harmless and is often more intense in dry conditions where static electricity can build up more easily.

The other options, while related to the context, do not directly explain the sensation of shock as effectively as the transfer of electrical charges does. For instance, while physical contact with a metal surface can facilitate the transfer of charges, it is specifically the jumping of electrical charges that causes the shock. The doorknob itself can accumulate static electricity, but it is the discharge event at the moment of contact that directly results in the zap. Friction between clothing and the floor contributes to the buildup of static