Question

In the above-given image, the part which is labelled as 7 is a

• A. Zero control
• B. UV mode selector
• C. Readout
• D. None of the above

Answer 1

Answer: (A)

Zero control

Photoelectric colorimeter uses a photocell, color filters, amplifiers and current detector. This device is used to measure the concentration of specific substance in a given solution. Its working is based on Beer-Lambert law. The zero control knob enables the pointer to be brought to its zero position at the line of the pointer scale when the Colorimeter lamp is on. The output from a colorimeter is displayed by this zero control knob.It is shown as transmittance (a linear scale from 0-100%) or as absorbance (a logarithmic scale from zero to infinity).