What instrument is used to verify LED warning light brightness and color accuracy?

• A. A photometric measurement device or calibrated light meter.
• B. A standard oscilloscope.
• C. A mercury thermometer.
• D. A voltage range tester.

Answer: (A)

Measuring how bright an LED warning light appears and whether its color matches the spec relies on instruments that quantify light output in perceptual terms and, for color accuracy, the spectral properties of the light. A photometric measurement device or calibrated light meter directly measures light intensity in photometric units (lux, luminance) and, with proper calibration, can verify that brightness meets the required threshold. It may also provide color-related readings depending on the model, giving a practical check of color output alongside brightness. In contrast, an oscilloscope analyzes electrical waveforms, not optical output; a mercury thermometer measures temperature; and a voltage range tester checks voltage—none of these assess light brightness or color.