Liquid Penetrant Testing Level 1 (PT-1) Practice Exam

Which condition is likely to decrease the life of a black light bulb?

1. High ambient temperature

2. Line voltage fluctuations

3. Constant voltage supply

4. Low usage frequency

The correct answer is: Line voltage fluctuations

Line voltage fluctuations can significantly decrease the life of a black light bulb due to the stress they impose on the bulb's electrical components. When the voltage fluctuates, it can lead to unexpected increases in current, causing the filament or other sensitive parts of the bulb to heat up excessively or operate outside of their intended parameters. Such conditions can lead to premature failure or burn out. Black light bulbs, also known as ultraviolet (UV) lamps, are designed to operate within a specific voltage range. When subjected to variations in line voltage, they may not only fail to emit the appropriate wavelength of UV light, but the mechanical and thermal stress may also cause physical damage to the bulb itself. Ultimately, maintaining a stable and consistent voltage supply is crucial for prolonging the life of black light bulbs used in liquid penetrant testing, as it ensures that they function efficiently and safely without undue stress.