Physics – Visible Light Range What is the approximate wavelength range of the visible spectrum perceived by the human eye (express your choice in angstrom units)?

Introduction / Context:
The visible spectrum corresponds to the wavelengths of electromagnetic radiation that stimulate the human visual system, spanning violet to red. Familiarity with this range is important in optics, photometry, and spectroscopy, and helps relate units like nanometres and angstroms.

Given Data / Assumptions:

• 1 angstrom (Å) = 10^-10 m; 1 nm = 10 Å.
• Typical visible range in nm ≈ 390–760 nm (often quoted as ~400–700 nm).
• We must choose the angstrom interval matching that range.

Concept / Approach:
Converting nm to Å: multiply by 10. Thus 390–760 nm becomes 3900–7600 Å. Options suggesting 1300–3000 Å are in the ultraviolet; values near 8500–9800 Å are near the infrared. The narrow 7800–8000 Å band is far too small to represent the entire visible spectrum.

Step-by-Step Solution:

Verification / Alternative check:
Check colour anchors: violet ~400 nm (4000 Å), red ~700–760 nm (~7000–7600 Å). The chosen option brackets these well, confirming correctness.

Why Other Options Are Wrong:

• 8500–9800 Å: Infrared region beyond red.
• 7800–8000 Å: Too narrow; also infrared boundary.
• 1300–3000 Å: Ultraviolet (far below visible).

Common Pitfalls:
Forgetting unit conversion between nm and Å. A quick tip: multiply nm by 10 to get Å; divide Å by 10 to get nm.

Final Answer:
3900 - 7600 angstrom