Waves S8P4a: Identify the characteristics of electromagnetic and mechanical waves. EQ: Why can’t you hear sound in space? What is a wave? • A disturbance or energy that travels through a medium or empty space from one location to another location – A medium is any form of matter which carries the waves • The energy moves from one location to another not the matter. • There are two categories of waves: Electromagnetic and Mechanical Electromagnetic Waves • Wave which is capable of transmitting its energy through a vacuum (empty space). Doesn’t need matter to transmit its energy. • Comes mainly from the sun • EX: UV, infrared, visible light, microwaves, x-rays, gamma rays, and radio waves • Most electromagnetic waves are transverse Transverse • Vibrates perpendicular (at right angles) to the wave travel – Most electromagnetic waves are transverse Animation courtesy of Dr. Dan Russell, Kettering University Transverse • Are Composed of – Crests- The highest point of a wave and – Troughs- The lowest point of a wave Mechanical Waves • Are not capable of transmitting its energy through a vacuum (empty space). • Need or require a medium (matter) in order to transport their energy from one location to another • EX: Sound waves, seismic waves, and water waves • Most mechanical waves are compressional/longitudinal Longitudinal/Compressional • Vibrates parallel to (in the same direction of wave travel ) the other end of the medium without the actual movement of matter --- Most mechanical waves are longitudinal/compressional Animation courtesy of Dr. Dan Russell, Kettering University Longitudinal/Compressional • Are composed of – Compressions, where the parts of the medium (coils of the Slinky) are closer together than normal and – Rarefactions, where the parts of the medium are farther apart than normal Animation courtesy of Dr. Dan Russell, Kettering University Water Waves • A combination of longitudinal & transverse Animation courtesy of Dr. Dan Russell, Kettering University