Electromagnetic Spectrum

The electromagnetic spectrum spans an enormous range of wavelengths, and wavelength is inversely related to frequency through c = f\lambda. Gamma rays have the shortest wavelengths, typically below 10^{-12}\ \text{m}, followed by X-rays around 10^{-10}\ \text{m}, then visible light near 5 \times 10^{-7}\ \text{m}, and microwaves in the millimetre-to-centimetre range. Ordering by increasing wavelength therefore gives gamma rays < X-rays < visible light < microwaves. The option placing X-rays below gamma rays inverts their true order. The arrangement starting with microwaves lists decreasing, not increasing, wavelength. The final option scrambles the sequence entirely and misplaces visible light. Memorising the relative positions of these bands is explicitly required by the NCERT Electromagnetic Waves chapter, where the spectrum is presented from radio waves at the long-wavelength end to gamma rays at the short-wavelength end. As a consistency check, higher-energy radiation always has shorter wavelength, so gamma rays sitting at the smallest wavelength and microwaves at the largest among these four is exactly what is expected.