Constantan wire withstands less than copper because it has a higher electrical resistance. This higher resistance causes more heat to be generated when current flows through the wire, leading to a decrease in its ability to withstand high temperatures. Copper, on the other hand, has lower resistance and better heat conductivity, making it more suitable for applications where high temperatures are involved. **

Constantan is a copper-nickel alloy with a low thermal expansion and high electrical resistance, making it ideal for use in resistors and thermocouples. On the other hand, iron is a metallic element with a high thermal conductivity and magnetic properties. Constantan is non-magnetic, while iron is ferromagnetic. Additionally, constantan has a higher electrical resistance compared to iron. **

The specific resistance of metals generally increases with temperature due to the increased thermal vibrations of the metal atoms, which hinder the movement of electrons. In contrast, the specific resistance of graphite decreases with temperature due to the increased mobility of charge carriers at higher temperatures. Constantan, an alloy of copper and nickel, has a relatively stable specific resistance over a wide range of temperatures, making it useful for applications requiring stable resistance. **

Constantan conducts poorly or not at all because it is an alloy made of copper and nickel, which has a higher resistivity compared to pure copper. The presence of nickel in constantan increases the resistance of the material, making it less conductive. On the other hand, copper is a pure metal with high electrical conductivity due to its free electrons that can move easily through the material, allowing for efficient conduction of electricity. **

Constantan is an alloy made of copper and nickel, which has a higher resistivity compared to pure copper. This higher resistivity in constantan leads to poor conductivity or no conductivity at all. On the other hand, copper is a pure metal with a high number of free electrons, allowing for easy flow of electricity and high conductivity. This difference in the number of free electrons and resistivity between constantan and copper is the reason for their contrasting conductive properties. **

When the voltage is increased in a constantan wire, the electrical resistance also increases. This is because the increase in voltage causes an increase in the flow of current through the wire, which in turn leads to more collisions between the electrons and the atoms in the wire. These collisions impede the flow of electrons, resulting in an increase in resistance. Therefore, as the voltage increases, the electrical resistance of the constantan wire also increases. **

When the current is proportional to the voltage in a constantan wire, it means that the wire obeys Ohm's Law. Ohm's Law states that the current flowing through a conductor is directly proportional to the voltage applied across it, given that the temperature remains constant. In the case of a constantan wire, this proportionality indicates that the wire has a consistent resistance, meaning that as the voltage increases, the current flowing through the wire also increases in a linear manner. **

When the current in a constantan wire is proportional to the voltage, it means that the wire obeys Ohm's Law. This law states that the current flowing through a conductor is directly proportional to the voltage applied across it, given that the temperature remains constant. In the case of constantan wire, the relationship between current and voltage is linear, making it a good conductor for electrical circuits. This proportionality allows for predictable behavior and easy manipulation of the current by adjusting the voltage. **