JAMB Physics 2019 Paper

Concept:Radio waves are a type of electromagnetic wave.All electromagnetic waves travel through a vacuum at the same fixed speed.That speed is about $3.0 \times 10^{8}\ \text{m/s}$.Explanation:Radio waves belong to the electromagnetic spectrum.This spectrum also includes visible light, infrared, ultraviolet, X-rays, and gamma rays.Electromagnetic waves do not require a material medium to travel.In a vacuum, every electromagnetic wave moves with the speed of light, denoted by $c$.The accepted value is $c = 3.0 \times 10^{8}\ \text{m/s}$.The speed of sound is roughly $340\ \text{m/s}$, but sound is a mechanical wave, not an electromagnetic wave.Option B gives $3 \times 10^{6}\ \text{m/s}$, which is far too small for electromagnetic waves.Therefore, the only choice that matches the velocity of radio waves is $3 \times 10^{8}\ \text{m/s}$.Answer:Option C: $3 \times 10^{8}\ \text{m/s}$.