Final answer:
A spectrophotometer is used to measure the turbidity of a liquid by transmitting light through the sample and detecting the intensity of light reaching a detector. This allows for the estimation of bacterial cell density and requires a calibration curve for accurate interpretation of results based on turbidity readings.
Step-by-step explanation:
The tool that can be used to measure the turbidity of a liquid by measuring the transmission of light through the sample is a spectrophotometer. The spectrophotometer works by splitting white light into a spectrum and allowing the choice of the wavelength of light for the measurement. The intensity of the light passing through the bacterial cell suspension is measured and as the number of cells increases, the turbidity also increases, leading to less light reaching the detector. A decrease in light transmission correlates with higher cell densities. To accurately measure turbidity, a control tube with only broth should be used to account for the baseline light transmission. Furthermore, a calibration curve is essential in correlating turbidity readings to actual cell counts. Newer indirect methods of counting live cells include electronic detection techniques that can be integrated into spectrometry equipment.