Question

which is not a property of electromagnetic waves?
electromagnetic waves are transverse waves that travel up and down with crests and troughs.
electromagnetic waves can travel through a vacuum.
electromagnetic waves are longitudinal waves and travel using compressions and rarefactions.

Explanation:

Step1: Recall properties of electromagnetic waves

Electromagnetic waves are transverse waves. Transverse waves have crests and troughs. They can travel through a vacuum (e.g., light from the sun travels through space - a vacuum - to reach Earth).

Step2: Analyze the statement about longitudinal waves

Longitudinal waves use compressions and rarefactions. But electromagnetic waves are not longitudinal. Sound waves are longitudinal (in air), while electromagnetic waves (like light, radio waves etc.) are transverse.

Answer:

Electromagnetic waves are longitudinal waves and travel using compressions and rarefactions.