Question

A puppy was trapped by a current carrying wire and was barking for help, a little boy couldn't stop himself and rushed for help and tried to save the dog with his naked hands but was caught himself. A man passing nearby took a wooden stick and saved both of them. Why did he use a wooden stick?

Answer 1

Hint:That wooden stick was made of wood and wood comes in the category of insulators in terms conductors and insulators does not conduct electricity. As the circuit was not completed due to insulating material (wood), no potential difference was not created which is necessary for the conduction of current.

Complete answer:
All the elements are categorised in three types on the basis of conduction of electricity. They are:
Conductors: Conductors are materials which completely permit the flow of free electrons or charge carriers, as a result electricity can flow through these materials. The force required to make that current flow through the conductor is known as voltage.
Example: All metals of periodic table except Bismuth (Bi). Graphite is a non-metal and it is the only non-metal that can conduct electricity.

Insulators:Insulators are materials that hinder the flow of free electrons or charge carriers, as a result electricity cannot flow through them. Example: Plastics, wood, glass etc.

Semiconductors: Semiconductors are materials that lie in between conductors and insulators on the basis of conduction of electricity. They conduct electricity under certain special conditions. Unlike metals they conduct electricity with the help of holes too.

Holes: Due to external energy (temperature or radiation) when an electron goes from valence band to conduction band (i.e., bonded electrons become free) a vacancy of free electrons gets created in valence band, which has the same charge as that of electron but positive. This positively charged vacancy is termed as hole.

How does someone get electric shock?
Electricity flows from high voltage to low voltage. A person gets electric shock when that person comes into contact with an electrical energy source or electric carrying conductor. As the current carrying conductor is at higher voltage and earth acts as a low (zero) voltage hence a voltage difference is set up. Hence, electricity can flow.

Now when a person touches a current carrying wire or conductor, he completes the connection between the wire and earth (high voltage to low voltage) as a result electricity flows through a portion of the body causing a shock.Electric shocks may result in moderate to high damage or even death. The man passing nearby took a wooden stick because he knows that wood is an insulator and by using the insulator while helping the boy and puppy, he is safe from any type of electric shock which may be fatal.

Note:One must note that the reason of getting electric shock is the potential difference created across the two points of the body, many people think that touching a wire give an electric shock which is wrong perception, if someone just touch a wire without any contact with earth or any lower potential then he will not get any shock because current always need a close path for its movement. One can use plastic shoes or rubber gloves in order to avoid electric shock as these materials are insulators and do not conduct electricity.