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UV–visible spectrophotometer — reference view
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Instrument housing

Encloses the main optical assembly on this historical instrument. The internal light source and wavelength selector are not exposed in this view.

Zoom in, then drag to inspect. Keyboard: + / − to zoom, arrows to pan, 0 to reset. Tap the numbered markers to explore parts.

UV–visible spectrophotometer — reference view

Image: Naval Air Material Center; United States. Navy · Source / original · Public domain

Resized and converted to WebP; original colours retained.

UV–visible spectrophotometer

Photometry & pH

UV–visible spectrophotometer

UV-Vis · spectrometer

THE FIRST VIVA QUESTION

What is its use?

Measures absorbance at selected wavelengths or across a spectrum in compatible samples.

Tap a number to locate its part. Zoom, drag or use full screen to inspect the reference. Models and graduations can differ; check the actual apparatus used in your laboratory.

01 / IDENTIFICATION

How to recognise it.

  1. Main optical instrument housing
  2. Controls for photometric operation
  3. Readout may be external on historical models or integrated in modern systems
Tell the difference.

A filter colorimeter offers selected bands; a UV–visible spectrophotometer typically permits finer wavelength selection and UV measurements when its optics and cuvette allow. The reference shows a historical laboratory assembly with an external readout; its internal optics are not visible.

02 / NUMBERED PARTS

Point them out.

Choose a part to bring its numbered marker into view.

03 / WORKING PRINCIPLE

The science behind the reading.

The instrument selects a wavelength band and compares transmitted light with a reference to calculate absorbance.

04 / VIVA PRACTICE

Think first. Then reveal.

Explain your answer aloud before opening it.

01Why may quartz cuvettes be needed?
SUGGESTED ANSWER

Quartz transmits suitable ultraviolet wavelengths; ordinary glass absorbs much of the UV region.

02What is absorbance?
SUGGESTED ANSWER

A = log10(I₀/I), where I₀ is reference intensity and I is transmitted intensity.

03What is the role of a blank?
SUGGESTED ANSWER

It establishes a baseline for the cuvette and assay matrix at the measurement wavelength.

04Can high absorbance cause error?
SUGGESTED ANSWER

Yes. Stray light and low transmitted signal can cause nonlinearity; follow the validated assay range.

Read the references.

Teaching and clinical references are listed here. Image attribution and licence appear below the viewer.