The correct option for the metal used to make wires for safety fuses is option 2, which states "high resistivity and low melting point."
To understand this, let`s break down the options:
Option 1: "Very low resistivity and high melting point"
- Low resistivity would mean that the metal allows the flow of electric current easily. However, for safety fuses, we want a material that restricts the flow of current. Therefore, this option is incorrect.
- High melting point is not necessarily a requirement for safety fuses. The fuses are designed to melt and break the circuit in case of excessive current. Therefore, this part of option 1 is not necessary.
Option 2: "High resistivity and low melting point"
- High resistivity is desired in safety fuses because it causes the wire to heat up when current flows through it. This leads to the wire melting and breaking the circuit, protecting the electrical system from damage. Therefore, the high resistivity is necessary.
- Low melting point is also required in safety fuses. When the current exceeds the safe level, the heat generated causes the wire to reach its melting point quickly, effectively breaking the circuit and preventing further damage.
Option 3: "Low resistivity and