Final answer:
To minimize the induced charge and prevent a painful electric shock, individuals in dry regions use a full hand to make contact with metal surfaces, thereby decreasing charge separation and distributing the charge across a larger area.
Step-by-step explanation:
In regions of low humidity, individuals often develop a special way to open car doors or touch metal doorknobs to avoid electric shocks. This technique involves placing as much of the hand on the door handle or knob as possible, rather than just using the fingertips. The reason behind this method is to decrease the induced charge on the body. When touching a metal object with a larger surface area of the hand, the charge separation is decreased, as opposed to just using a fingertip which concentrates the charge at a point and can result in a painful spark. Full palm contact distributes the charge over a larger area, reducing the overall charge density and the likelihood of a resultant spark.
Moreover, this method of contact reduces the potential difference between the hand and the metal object, thereby reducing the current that flows when contact is made, which in turn reduces the severity of the static shock experienced. This spread of the electric charge over a larger area is a principle referred to as charging by conduction, and is practical in everyday life, especially in dry environments prone to static electricity buildup.