It's due to very low resistivity of silver , it allows free flow of current through it.

Best Conductor of Electric Current

Introduction:
Electricity is the flow of electric charge through a conductor. Conduction refers to the movement of charged particles, such as electrons, within a material. Different materials have different abilities to conduct electricity. Among the given options, silver is considered the best conductor of electric current.

Explanation:

1. Conductivity:
Conductivity is a measure of a material's ability to conduct electric current. It is determined by the number of free electrons available in a material and their ability to move through it. Materials with a higher number of free electrons and less resistance allow for better conduction of electricity.

2. Silver:
Silver has the highest electrical conductivity among all metals. It has a high number of free electrons, which are not strongly bound to the atomic nuclei, enabling them to move easily through the material. Due to this high mobility of electrons, silver exhibits excellent conductivity.

3. Copper:
Copper is the second-best conductor of electric current among the given options. It also has a high number of free electrons, making it an excellent conductor. Copper is widely used in electrical wiring and transmission lines due to its good conductivity and lower cost compared to silver.

4. Aluminium:
Aluminium is also a good conductor of electric current but not as efficient as silver or copper. It has fewer free electrons compared to silver or copper, resulting in relatively higher resistance. However, aluminium is lightweight and corrosion-resistant, making it suitable for certain applications.

5. Iron:
Iron is not as good a conductor of electric current as silver, copper, or aluminium. It has fewer free electrons and higher resistance, making it less efficient in conducting electricity. Iron is commonly used in electrical transformers and electromagnets due to its magnetic properties rather than its conductivity.

Conclusion:
Among the given options, silver is the best conductor of electric current due to its high number of free electrons and low resistance. Copper is the second-best conductor, followed by aluminium. Iron has lower conductivity compared to the other three metals.