Which statement best describes the effect of increasing the bandpass width on spectral resolution?

Which statement best describes the effect of increasing the bandpass width on spectral resolution?

• A. Increases resolution
• B. Decreases resolution
• C. No effect on resolution
• D. Improves linearity of measurements

Answer: (B)

Increasing the bandpass width reduces spectral resolution because you’re letting through a broader range of wavelengths. When the instrument accepts a wider Δλ, signals from nearby wavelengths blend together, making it harder to distinguish closely spaced spectral features. This is captured by the idea that spectral resolution is related to how finely you can separate wavelengths, often expressed as R ≈ λ/Δλ; as Δλ grows, R decreases, so the ability to resolve fine details diminishes. There’s a trade-off to keep in mind: a wider bandpass increases throughput and improves signal strength, but at the cost of resolving power. A narrower bandpass limits the range of wavelengths admitted, boosting resolution and enabling you to separate close lines, though it reduces the overall signal. For example, trying to resolve two nearby emission lines becomes much easier with a narrow bandpass than with a wide one. So, increasing the bandpass width leads to lower spectral resolution.

Increasing the bandpass width reduces spectral resolution because you’re letting through a broader range of wavelengths. When the instrument accepts a wider Δλ, signals from nearby wavelengths blend together, making it harder to distinguish closely spaced spectral features. This is captured by the idea that spectral resolution is related to how finely you can separate wavelengths, often expressed as R ≈ λ/Δλ; as Δλ grows, R decreases, so the ability to resolve fine details diminishes.

There’s a trade-off to keep in mind: a wider bandpass increases throughput and improves signal strength, but at the cost of resolving power. A narrower bandpass limits the range of wavelengths admitted, boosting resolution and enabling you to separate close lines, though it reduces the overall signal. For example, trying to resolve two nearby emission lines becomes much easier with a narrow bandpass than with a wide one.

So, increasing the bandpass width leads to lower spectral resolution.