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Foundation3 past questions

Electromagnetic spectrum

The electromagnetic spectrum encompasses all types of electromagnetic waves, classified by wavelength or frequency, with each region having characteristic properties and applications.

Why this shows up in the exam

NEET expects you to identify, order, and understand the uses of different regions of the electromagnetic spectrum.

How NEET tests this

Match the columnsDirect recallSequence / ordering

Learn the idea

The electromagnetic spectrum is a continuous range of waves ordered by wavelength (or frequency); remembering that longer wavelength ↔ lower frequency unlocks every ordering problem.

🧠 Memory hook: R M I V U X G – “Rabbits Make Incredible Very Ugly X‑ray Gifts”, the letters stand for Radio, Microwave, Infrared, Visible, Ultraviolet, X‑ray, Gamma.

Get this one clearly and it pays off every single time it shows up in the paper. 🎯

Formulas & facts to keep ready

  • Electromagnetic spectrum regions: radio, microwave, infrared, visible, ultraviolet, X‑ray, gamma ray (NCERT)
  • Wavelength λ = c / frequency f (c = 3×10⁸ m s⁻¹)
  • Order of decreasing wavelength: Radio > Microwave > Infrared > Visible > Ultraviolet > X‑ray > Gamma
  • Photon energy increases as wavelength decreases (E = h f)
  • Typical applications: radio – communication; microwave – cooking, radar; infrared – heating, remote sensing; ultraviolet – sterilisation; X‑ray – medical imaging; gamma – nuclear processes

How to approach it

  1. 11 Identify the spectral regions mentioned in the question.
  2. 22 Recall the standard order of decreasing wavelength (or increasing frequency).
  3. 33 Place each region in that order; if numbers are given, compare their powers of ten.
  4. 44 Choose the option that matches the arranged sequence.

Worked example — watch it click

The decreasing order of wavelength of infrared, microwave, ultraviolet and gamma rays is:

  • ✅Microwave, infrared, ultraviolet, gamma rays.
  • B)Gamma rays, ultraviolet, infrared, microwaves.
  • C)Microwaves, gamma rays, infrared, ultraviolet.
  • D)Infrared, microwave, ultraviolet, gamma rays.

The concept behind this problem

The worked example asks for the decreasing order of wavelength of four given regions, directly testing the student’s recall of the spectrum’s hierarchy.

Step by step

  1. 1In the electromagnetic spectrum, wavelength decreases (frequency increases) in the order: Radio waves > Microwaves > Infrared > Visible > Ultraviolet > X-rays > Gamma rays.
  2. 2Therefore, the decreasing order of wavelength for the given options is: Microwave > Infrared > Ultraviolet > Gamma rays.

Watch out

Students often place infrared before microwave, forgetting that microwaves have the longer wavelength.

Common slip-ups that cost marks

  • •Do not confuse wavelength with frequency – the longer the wavelength, the lower the frequency.
  • •Microwave wavelengths are longer than infrared; many students invert this pair.
  • •Never rely on colour‑based intuition for invisible regions; stick to the memorised order.

🌟 That's the whole idea — you've got this. Try the practice set below; every question you attempt makes it stick a little harder.

Practise it

These are real questions from past NEET papers that test this exact idea.

Question 1 of 3NEET 2022

Match List-I with List-II: List-I (Electromagnetic Waves) (1) AM radio waves (2) Microwaves (3) Infrared radiations (4) X-rays List-II (Wavelength) (i) 10⁻¹⁰ m (ii) 10² m (iii) 10⁻² m (iv) 10⁻⁴ m

Push further

More challenging

3 harder questions built from the past papers above — a step up in difficulty, with distractors designed so you can't get there by elimination. Written and checked by our reviewers, not from a real paper.

Question 1 of 3

An electromagnetic wave is used in medical imaging to visualize bone structures. Which of the following properties is most characteristic of this wave?

More from Electromagnetic Waves