SACE Stage 2 Physics Practice Exam 2025 – Full Prep Resource

Electromagnetic waves travel in a vacuum at a speed commonly referred to as the speed of light, which is approximately 3 x 10^8 meters per second. This speed is a fundamental constant in physics, denoted by the symbol 'c'. It represents the maximum speed at which information or matter can travel in the universe according to the theory of relativity.

The value of 3 x 10^8 ms^-1 signifies that, in a vacuum, electromagnetic waves—including visible light, radio waves, microwave radiation, and other forms of electromagnetic radiation—propagate at this consistent speed. This consistency is crucial for various applications, including telecommunications, astronomy, and modern physics experiments, where precise calculations of wave behavior and interactions are essential.

The other values provided in the choices are significantly different from the accepted speed of electromagnetic waves in a vacuum, which further emphasizes why 3 x 10^8 ms^-1 is the correct answer. Understanding this speed is fundamental when studying wave phenomena, light, and the principles of electromagnetism.