Question

In a spectrophotometer, the monochromator must be able to resolve two wavelengths 599.9 nm and 600.1 nm. The required resolution is:

• A. 100
• B. 500
• C. 1000
• D. 3000

Hint:

Resolution in spectrophotometers is calculated by dividing the average wavelength by the difference to be resolved.

Answer 1

The Correct Option is D

The resolution $R$ of a monochromator is defined as:
\[ R = \dfrac{\lambda}{\Delta \lambda} \]
Where:
- $\lambda$ is the average wavelength
- $\Delta \lambda$ is the minimum difference between two wavelengths that the instrument can distinguish
Given:
$\lambda_1 = 599.9$ nm
$\lambda_2 = 600.1$ nm
Average wavelength $\lambda = \dfrac{599.9 + 600.1}{2} = 600$ nm
Difference $\Delta \lambda = 600.1 - 599.9 = 0.2$ nm
Now compute resolution:
\[ R = \dfrac{600}{0.2} = 3000 \]
Therefore, the required resolution of the monochromator is 3000.