Exam Question

### (a) Types of Temperature Sensing Devices for Remote Indication
Three primary types of temperature sensing devices used for remote indication in marine applications are:
1. **Thermocouples**: These devices operate on the Seebeck effect, generating a small voltage (EMF) proportional to the temperature difference between two junctions of dissimilar metals. They are robust, have a wide temperature range, and are commonly used for high-temperature applications like exhaust gas monitoring.
2. **Resistance Temperature Detectors (RTDs)**: These sensors work on the principle that the electrical resistance of a pure metal (commonly Platinum, e.g., Pt100) changes in a precise and repeatable manner with temperature. They offer high accuracy and stability, making them suitable for critical measurements like lube oil, jacket water, and cargo temperatures.