| If an oil-in-water content monitor uses a lamp emitting light in the visible spectra in conjunction with a reference photo-cell and a sampling photocell, what is the operating principle upon which this oil-in-water content monitor works? |
| A) The monitor works on the fluorescence principle where the greater the oil content, the less the amount of ultra-violet light detected by the sampling photo-electric cell as compared to the reference photo-electric cell. |
| B) The monitor works on the absorption/scattering principle where the greater the oil content, the less the amount of visible light detected by the sampling photo-electric cell as compared to the reference photo-electric cell. |
| C) The monitor works on the fluorescence principle where the greater the oil content, the greater the amount of ultra-violet light detected by the sampling photo-electric cell as compared to the reference photo-electric cell. |
| D) The monitor works on the absorption/scattering principle where the greater the oil content, the greater the amount of visible light detected by the sampling photo-electric cell as compared to the reference photo-electric cell. |
