How to control the current/voltage in resistive wires
For a fixed length of wire you can control either voltage or current. Controlling one will control the other by Ohm's Law, \$ V = IR \$ although the resistance will increase as the wire heats up.

Controlling either V or I will adjust power (P) which is measured in watts (W).

To control temperature&mdash;to heat to 80°C, for example&mdash;requires a temperature sensor wired to a temperature controller and something to switch the current off when setpoint is reached.

The simplest solution is to use a thermostat.







simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. Thermostat and heater wiring. When the thermostat setpoint is exceeded the contact will open and shut off the power.