Which one of the following is NOT true for an electromagentic wave?

Electromagnetic (EM) waves are fundamentally transverse waves, not longitudinal waves [1]. In a transverse wave, the disturbances—specifically the oscillating electric and magnetic field vectors—occur in a plane perpendicular to the direction of wave propagation [1]. Conversely, longitudinal waves, such as sound, involve disturbances parallel to the direction of travel [1]. EM waves are characterized by varying electric and magnetic fields that are mutually perpendicular [1]. They transport both energy and momentum, which can be described using the Poynting vector. Furthermore, because they are transverse, EM waves exhibit unique properties such as polarization, which is the restriction of the electric field's vibration to a specific plane. They also undergo standard wave phenomena like reflection and refraction when encountering different media. Therefore, the statement that EM waves are longitudinal is incorrect.

Sources

1. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 5: Earths Magnetic Field (Geomagnetic Field) > Why Do Sound Waves Travel Faster In A Denser Medium Whereas Light Travels Slower? > p. 64
2. [1] https://www.sciencedirect.com/topics/social-sciences/electromagnetic-wave