# Unit 4 Lesson 1 Waves What are waves

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Unit 4 Lesson 1 Waves

What are waves? A disturbance that transfers energy from one place to another without moving the matter the entire way. A medium is the material through which a wave can travel.

What are waves? • The points where a wave is highest are called crests. The points where a wave is lowest are called troughs. Wave Travels

• Some waves, such as ocean waves, transfer energy through a medium. • Some waves, such as light waves, can transfer energy without a medium. Water, rope and the ground are all examples of a medium or matter that can carry waves.

How does a wave transfer energy? • A wave transfers energy in the direction it travels. • Waves can be classified by the direction that they cause the medium to move and the direction the energy travels.

How can energy be passed along? In your 3 Minute Warm Up, write down the answers to these questions. 1. How far did each video move? 2. What traveled from the beginning to the end of the line? 3. Where did the energy to move the last video come from?

1) Longitudinal Wave Energy is transferred in the same direction as the disturbance. T D compression Example: sound waves rarefaction

Longitudinal Waves

2) Transverse Wave Energy is transferred from one object to another using up and down motions. They move perpendicular to the force that started them. T crest D trough Examples: water waves, “The Wave” and in a rope.

Transverse Waves

Transverse wave

What are some types of waves? Mechanical waves transfer ___________ energy through a medium (matter). • Some mechanical waves can travel through more than one medium. • For example, sound waves can move through air, water, and a solid wall. • Mechanical waves can’t travel without a medium.

What are some types of waves? ___________ Electromagnetic waves a disturbance in electric and magnetic fields • Sunlight is an example of EM waves. Other examples include radio waves, microwaves, and X-rays. • In empty space, all EM waves travel at the same speed, called the speed of light.

Electromagnetic mechanical waves mechanical wave electromagnetic wave