A student investigates how the resistance of a specialized metal wire coil varies with temperature. The student heats a beaker of paraffin oil containing the wire coil and a thermometer, and measures the potential difference across the coil for a constant current.
The diagram shows the student's initial apparatus setup:
Suggest three changes to this experimental setup that would improve the accuracy of the temperature measurement of the wire coil.
What instrument should the student use to measure the potential difference across the wire coil?
State the equation linking potential difference (voltage), current, and resistance.
At a particular temperature, the wire coil has a resistance of 250 Ω250\ \Omega250 Ω. If the potential difference across it is 6.0 V6.0\text{ V}6.0 V, calculate the current in the coil in milliamperes (mA\text{mA}mA).