Question

Which device is used to isolate the radiation of the desired wavelength from wavelength of the continuous spectra?

• A. source
• B. detector
• C. monochromator
• D. isolator

Hint:

"Mono" means single, and "chroma" means color.
A monochromator is literally a "single-color creator" that takes polychromatic light as input and outputs monochromatic light.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks to identify the optical component in a spectrophotometer that isolates a specific single wavelength (or a narrow band of wavelengths) from a broad continuous spectrum.

Step 2: Detailed Explanation:

• A spectrophotometer requires monochromatic light (light of a single wavelength) to perform accurate absorption analysis based on Beer's Law.

• The light source generally emits a broad, continuous spectrum containing many wavelengths (such as white light from a tungsten lamp).

• To select the desired wavelength, a Monochromator is used.

• A monochromator typically consists of:

• An entrance slit to collimate incoming light.

• A dispersing element (either a prism or a diffraction grating) to break the continuous spectrum into its constituent colors (wavelengths).

• An exit slit to block all unwanted wavelengths and transmit only the narrow band of the desired wavelength.

• Hence, the monochromator is the device responsible for isolating the target wavelength.

Step 3: Final Answer:
The monochromator is used to isolate the desired wavelength from a continuous spectrum.