G2 Gas Fitter Practice Exam

Identify the statement that best describes flame rectification.

1. The flame reflects light better than other surfaces

2. The flame conducts electrons better from the flame-rod to ground than from ground to flame rod

3. The flame absorbs heat better from the ground than from the rod

4. The flame emits infrared radiation effectively

The correct answer is: The flame conducts electrons better from the flame-rod to ground than from ground to flame rod

The statement that best describes flame rectification is that the flame conducts electrons better from the flame-rod to ground than from ground to flame rod. This principle is fundamental in gas appliances equipped with flame sensing systems. In flame rectification, the flame acts as a conductive path for electrical current. When a burner is operating, the flame can ionize the gases present, creating a charged path for the flow of electrons. This ionization allows for a better flow of current (electrons) from the ground through the flame back to the flame rod, confirming the presence of a flame. If the flame were to go out, the conductivity would drastically decrease, causing the current flow to stop, which is a critical safety feature in gas appliances to prevent unburned gas from accumulating in the combustion area. The other options do not accurately describe the specific function of flame rectification. For instance, while the flame may emit infrared radiation or reflect light in a certain way, these characteristics do not relate to the principle of flame rectification and the importance of electrical conductivity in a flame-sensing mechanism. Similarly, the statements about heat absorption do not pertain to the electrical conduction properties that are pivotal to flame rectification's operation.