The correct answer is option 1: high specific resistance and low melting point.
An electric fuse is a safety device that is designed to protect electrical circuits from excessive current. When an electrical circuit experiences a surge in current, the fuse will melt and break the circuit, preventing damage to the components or potential fire hazards.
In order to fulfill its purpose effectively, the material used for the electric fuse should possess specific characteristics. The alloy of tin and lead is often chosen for this purpose because it meets these requirements.
Firstly, the material should have high specific resistance. Specific resistance is a measure of how much a material resists the flow of electric current. By having a high specific resistance, the alloy of tin and lead can limit the amount of current flowing through the circuit.
Secondly, the material should have a low melting point. This is important because when excessive current flows through the circuit, the fuse should be able to melt and break the circuit quickly. A low melting point ensures that the fuse responds rapidly to the surge in current and protects the circuit from damage.
In summary, the material used for the electric fuse should have high specific resistance to limit the current and a low melting point to allow it to melt quickly and break the circuit. Option 1 correctly describes these