Final answer:
The claim that thermocouple transmitters output is 0-15 mA is false; they typically output a 4-20 mA signal. This standard helps distinguish between a live zero and a disconnected signal in current loop control systems, which is essential for circuit design and electrical safety.
Step-by-step explanation:
The statement that thermocouple transmitters generally produce 0-15 mA output signals is false. Thermocouple transmitters typically produce a standard signal of 4-20 mA for current loop systems. The 4-20 mA signal is one of the most widely used for transmitting sensor signals to a control system. A zero signal (0 mA) is not used because it would not allow for the distinction between no signal (due to a cut wire, for example) and the lowest value of the measured parameter. Therefore, the 4 mA point represents the lower end of the scale, while 20 mA represents the upper end.
Adhering to Ohm's law is crucial for understanding and designing circuits with consistent current flow, ensuring electrical safety in the development of systems and devices. For instance, the use of digital devices over analog devices in null measurements can improve the accuracy due to their sensitivity to smaller currents, allowing for a current closer to zero. Also, true safety devices like isolation transformers ensure that considerations such as resistance variations due to temperature changes or potential safety hazards, like in high-voltage systems, are appropriately addressed.