Which one of the following is NOT a correct property of electromagnetic waves?

Introduction / Context:
Electromagnetic waves, such as light, radio waves, X rays, and microwaves, share a set of common properties described by Maxwell's theory and classical wave optics. Understanding which statements correctly describe these waves is fundamental for topics ranging from communication technology to quantum physics. This question asks you to identify which listed statement is not a true property of electromagnetic waves, so you must recall their key wave characteristics.

Given Data / Assumptions:
• We are dealing with electromagnetic waves like visible light, radio waves, and X rays. • Statements mention interference, diffraction, field directions, nature of the waves, and propagation without a medium. • We assume standard physics definitions of interference and diffraction.

Concept / Approach:
Electromagnetic waves consist of oscillating electric and magnetic fields, mutually perpendicular and also perpendicular to the direction of propagation, making them transverse waves. They can travel through vacuum, which is why we receive sunlight from the Sun across empty space. As waves, they show all typical wave phenomena, including reflection, refraction, interference, and diffraction. Interference and diffraction are strong experimental proofs of the wave nature of light. Therefore, any statement claiming that electromagnetic waves do not show interference and diffraction is false.

Step-by-Step Solution:
Step 1: Recall that in Young's double slit experiment, visible light shows clear interference fringes, proving that electromagnetic waves can interfere. Step 2: Note that light also bends around obstacles and through slits of size comparable to its wavelength, demonstrating diffraction. Step 3: Recognise that electromagnetic waves are transverse; the electric and magnetic fields oscillate perpendicular to each other and to the direction of propagation. Step 4: Understand that electromagnetic waves can travel through vacuum without any material medium and in vacuum they travel at the speed of light, c. Step 5: From these facts, conclude that the incorrect statement is the one claiming electromagnetic waves do not show interference and diffraction.

Verification / Alternative check:
Numerous experiments confirm interference and diffraction of light. Optical instruments are designed with diffraction limits in mind, and radio antennas are built considering interference and diffraction patterns. These behaviours are not limited to visible light but occur across the full electromagnetic spectrum. Therefore, any claim that electromagnetic waves do not show interference and diffraction contradicts well established experimental results and must be the false property in the list.

Why Other Options Are Wrong (i.e., they are actually correct properties):
Option b: Electromagnetic waves have electric and magnetic fields oscillating perpendicular to each other, a direct result of Maxwell's equations. Option c: They are transverse waves because field oscillations are perpendicular to the direction of propagation. Option d: They do not require a medium; they can travel through vacuum, which is why sunlight reaches Earth. Option e: In vacuum, all electromagnetic waves travel at the same speed, the speed of light, denoted by c.

Common Pitfalls:
Some students mistakenly think only water waves or sound waves show interference and diffraction, forgetting that these are general wave phenomena. Another confusion is between sound (which is a mechanical wave and needs a medium) and electromagnetic waves (which do not). Always remember that interference and diffraction are strong evidence for wave nature and apply to electromagnetic waves as well.

Final Answer:
The statement that is NOT a correct property of electromagnetic waves is: Electromagnetic waves do not show interference and diffraction.