Question

A colorimeter (photometric) determination involves the measurement of colour in which region of the electromagnetic spectrum?

• A. Infrared
• B. Ultraviolet
• C. Visible
• D. Microwave

Hint:

Colorimetry = visible light absorption. Spectrophotometry = visible + UV + IR regions.

Answer 1

The Correct Option is C

Step 1: Understand Colorimetry Principles.
A colorimeter quantifies light absorbance by a colored solution. Beer-Lambert's law dictates that absorbed light intensity is directly proportional to solution concentration.
Step 2: Identify Operational Wavelength Range.
Visible light, encompassing wavelengths from 400 to 700 nm, is the basis of color. Therefore, a colorimeter functions within the visible spectrum.
Step 3: Eliminate Inapplicable Spectroscopic Regions.
- (A) Infrared: Employed in IR spectroscopy, not colorimetry.
- (B) Ultraviolet: Utilized in UV spectrophotometry.
- (C) Visible: Accurate, as colorimetry measures absorption in the visible range.
- (D) Microwave: Applied in communication and radar, not photometry.
Step 4: Final Determination.
Colorimetric analysis necessitates measurement within the visible electromagnetic spectrum.