Correct Option: (b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).

Step 1 (Foundational Concept): [0.5 Mark]

The Assertion (A) is based on the nature of electromagnetic (EM) waves. According to Maxwell's equations, EM waves are produced by oscillating charges, which create time-varying electric fields ($\vec{E}$) and magnetic fields ($\vec{B}$). These fields regenerate each other in free space, allowing propagation without a material medium.

Step 2 (Analysis of Reason): [0.25 Mark]

The Reason (R) states that EM waves are transverse. This is true because the electric field vector $\vec{E}$ and magnetic field vector $\vec{B}$ oscillate perpendicular to each other and perpendicular to the direction of wave propagation ($\vec{k}$):

Step 3 (Final Conclusion): [0.25 Mark]

While both statements are scientifically accurate, the fact that EM waves are transverse (Reason) is not the cause for their ability to travel through a vacuum. Their ability to travel through a vacuum is due to the self-sustaining nature of the oscillating fields. Therefore, (R) is not the correct explanation for (A).

💡 EL10 Concept Insight:

Think of EM waves like a self-propelling relay race: the electric field creates a magnetic field, which then creates an electric field, allowing the wave to "walk" through empty space all by itself! Being "transverse" just describes the shape of the wave's wiggle, not the reason it doesn't need a medium.