To measure high temperatures up to 2400 degrees F, you would use:

To measure high temperatures up to 2400 degrees Fahrenheit, thermocouples are particularly effective. They operate on the principle that a voltage is generated when there is a temperature difference between two different conductors. This characteristic makes them suitable for extreme temperatures, as they can accurately measure heat in environments that would exceed the capabilities of other types of temperature sensors.

On the other hand, bi-metal strip thermometers function by expanding different metals at different rates, which can also be useful for temperature measurement but typically do not reach the upper limits of 2400 degrees F effectively. They are generally used for lower temperature applications.

Resistance thermometers, or RTDs, measure temperature by correlating the resistance of a metallic element to temperature changes, but they generally operate within lower temperature ranges compared to thermocouples.

By choosing both thermocouples and bi-metal strip thermometers, the response encompasses both options that can be relevant for temperature measurement, especially under high-temperature conditions. Thus, the inclusion of thermocouples in the approach makes it a robust selection for accurately measuring very high temperatures.