Which of the following best describes the relationship between the wavelength and frequency of a spectral line for lithium chloride (LiCl)?

• A. Wavelength and frequency are independent of each other.
• B. As the frequency increases, the wavelength remains constant.
• C. As the wavelength increases, the frequency increases.
• D. As the wavelength increases, the frequency decreases.

Answer: (D)

Verified step by step guidance

1. Recall the fundamental relationship between the wavelength (\( \lambda \)) and frequency (\( \nu \)) of electromagnetic radiation, which is given by the equation: \[ c = \lambda \times \nu \] where \( c \) is the speed of light in a vacuum (approximately \( 3.00 \times 10^{8} \, \text{m/s} \)).
2. Understand that the speed of light \( c \) is a constant, so any change in wavelength must be accompanied by a corresponding change in frequency to keep the product \( \lambda \times \nu \) constant.
3. Rearrange the equation to express frequency in terms of wavelength: \[ \nu = \frac{c}{\lambda} \] This shows that frequency is inversely proportional to wavelength.
4. Interpret the inverse relationship: as the wavelength \( \lambda \) increases, the frequency \( \nu \) must decrease to maintain the constant speed of light, and vice versa.
5. Apply this understanding to the spectral lines of lithium chloride (LiCl), which are forms of electromagnetic radiation; therefore, the correct description is that as the wavelength increases, the frequency decreases.