Electromagnetic spectrum coverage: Which of the following wavelength domains are part of the EM spectrum?

Introduction / Context:
The electromagnetic (EM) spectrum spans an enormous range of wavelengths and frequencies, from extremely high-energy gamma rays to low-frequency radio waves. Many remote-sensing instruments and communication systems occupy specific windows within this spectrum.

Given Data / Assumptions:

• Approximate wavelength bounds are used; exact ranges overlap by convention.
• Statements b and c use inequality cutoffs that include substantial portions of the UV and IR domains, respectively.
• Radio waves generally include metre-scale and longer wavelengths.

Concept / Approach:
Despite differing conventional boundaries, the listed domains—gamma, UV, IR, and radio—are indisputably part of the EM spectrum. The inequalities provided are broadly consistent with common textbook partitions (e.g., UV shorter than visible, IR longer than visible up to millimetre and beyond, radio long-wavelength regime).

Step-by-Step Solution:
Confirm gamma rays occupy the shortest wavelengths (well below 10^-10 m).UV extends below roughly 4×10^-7 m; “< 10^-6 m” certainly covers UV and more.IR spans ~0.7 μm to 1 mm; “< 10^-4 m” captures near/mid IR portions.Radio waves include wavelengths greater than 1 m among many bands.Therefore, all listed domains belong to the EM spectrum.

Verification / Alternative check:
Standard EM spectrum charts show continuous coverage across these regions; instrument bands (e.g., thermal IR ~10 μm, L-band radar ~23 cm) sit within the stated ranges.

Why Other Options Are Wrong:
Any single selection would ignore the fact that all mentioned categories are genuine EM regions.

Common Pitfalls:
Over-interpreting the inequalities as exact definitions; boundaries are conventional and application-dependent but do not change membership in the EM spectrum.

Final Answer:
All of these.