Which device isolates light within a narrow region of the spectrum?

Which device isolates light within a narrow region of the spectrum?

• A. Photomultiplier tube
• B. Monochromator
• C. Photovoltaic cell
• D. Detector

Answer: (B)

Isolating light to a narrow region of the spectrum is achieved by a monochromator. It uses a dispersive element, such as a diffraction grating or a prism, to separate light into its component wavelengths. By adjusting the exit slit, you transmit only a small range of wavelengths, producing nearly monochromatic light. This spectral selection is essential in spectroscopy because it lets you study how a sample interacts with light at a specific wavelength and reduces interference from other wavelengths. A photomultiplier tube is a highly sensitive detector that amplifies photons but does not inherently isolate wavelengths. A photovoltaic cell converts light to electrical energy and isn’t selective for wavelength. A detector, in general, senses light but won’t limit the signal to a narrow spectral band without an accompanying spectral filtering element.

Isolating light to a narrow region of the spectrum is achieved by a monochromator. It uses a dispersive element, such as a diffraction grating or a prism, to separate light into its component wavelengths. By adjusting the exit slit, you transmit only a small range of wavelengths, producing nearly monochromatic light. This spectral selection is essential in spectroscopy because it lets you study how a sample interacts with light at a specific wavelength and reduces interference from other wavelengths. A photomultiplier tube is a highly sensitive detector that amplifies photons but does not inherently isolate wavelengths. A photovoltaic cell converts light to electrical energy and isn’t selective for wavelength. A detector, in general, senses light but won’t limit the signal to a narrow spectral band without an accompanying spectral filtering element.