NCCER Millwright Practice Exam

Imperfect performance by a laser in the atmosphere is caused by what factor?

1. Humidity or dust

2. Temperature fluctuations

3. Pressure variations

4. Distance from source

The correct answer is: Humidity or dust

Imperfect performance by a laser in the atmosphere is significantly influenced by humidity or dust. When a laser beam passes through the atmosphere, particles such as dust or water vapor can scatter, absorb, or refract the light, leading to attenuation and distortion of the laser signal. High humidity levels can lead to increased scattering, especially if the drops of water are of a size comparable to the wavelength of the laser light. Dust particles can also impair the clarity and precision of the beam, reducing its effectiveness for applications such as measuring distances or communicating data. In contrast, while temperature fluctuations, pressure variations, and distance from the source can affect the behavior of a laser beam, they generally do not have as direct or impactful an influence on the beam's performance as the presence of humidity or dust in the atmosphere. Temperature and pressure changes may alter the medium the laser travels through, potentially impacting its speed or focusing capabilities, but they are less significant in terms of causing immediate performance degradation compared to particulate matter in the air.