Which of the following metals has the lowest resistivity at 20°C?

• A. Aluminum
• B. Brass
• C. Copper
• D. Silver

Answer: (D)

Silver has the lowest resistivity among the metals listed at 20°C, making it the best conductor of electricity. The resistivity of a material is a crucial property that reflects how strongly it resists the flow of electric current. Silver's resistivity is approximately 1.59 µΩ·m, which is lower than that of the other metals mentioned.

In comparison, copper, while also an excellent conductor with a resistivity around 1.68 µΩ·m, falls slightly short of silver's conductive properties. Aluminum and brass have even higher resistivities, with aluminum around 2.65 µΩ·m and brass being significantly higher due to its composition, which includes zinc and copper. The ability of a metal to conduct electricity well is primarily attributed to its atomic structure, particularly the presence of free electrons. Silver's atomic structure allows for a greater number of these free electrons compared to the other metals, resulting in superior conductivity.

Considering this information, silver is recognized as the standard for electrical conductivity, which is why it is the correct answer to the question regarding the metal with the lowest resistivity at 20°C.