PHYSICAL SCIENCEWaves and Electromagnetic Radiation

Bell RingerWith Spring Break coming up, some of us will be viewing WAVES up close and personally! Hopefully all of us will experience an increased

amount of waves from the electromagnetic spectrum.

1. Write down everything you know about WAVES in a KWHL chart. We will discuss this in class.

Objectives For Today:

•Today we are:• Building an understanding of waves and common wave terminology

Agenda/Announcements!

•Bell Ringer

•Introduction to WAVES and electromagnetic radiation

What are waves?

Wave

•Definition: A disturbance that transfers energyfrom place to place.

•What is it that carries a wave? A medium is the material through which a wave travels.

•A medium can be a gas, liquid, or solid.

NOT ALL WAVES REQUIRE A MEDIUM TO

TRAVEL.* But most do. The exception would be light from the sun travelling

through empty space.

What causes waves?

•Waves are created when a source of energy causes a medium to vibrate.

•A vibration is a repeated back and forth or up and down motion.

TYPES of waves: Waves are classified according to how they move.

Transverse wave• Waves that move the medium at

right angles to the direction in which the waves are traveling is called a transverse wave.

• Transverse means “across”. The highest parts are called crests the lowest parts are called troughs.

• Examples: Ocean waves, Light waves

Compressional Wave

•Matter vibrates in the same direction as the wave travels.

•Example: Slinky, Sound

Compressional wave

•The parts where the coils are close together are called compressions, the parts where the coils are spread out are called rarefactions.

PROPERTIES OF WAVES

Basic Properties of Waves: Terms you will need to know:

•Amplitude

•Wavelength

•Frequency

•Speed

Amplitude

•Amplitude is the maximum distance the particles of the medium carrying the wave move away from their rest positions.

•The farther the medium moves as it vibrates the largerthe amplitude of the resulting waves. The greater the amplitude the greater the amount of energy

Amplitude• You can find the amplitude of a transverse

wave by measuring the distance from rest to crest or rest to trough.

• The amplitude of a compressional wave can be found by checking the density of the material in the compressions and rarefactions.

Wavelength

• A wave travels a certain distance before it starts to repeat. The distance between two corresponding parts of a wave is its wavelength.

• Transverse measure from crest to crest or trough to trough.

• Compressional wavelengths are measured from one compression to the next.

Frequency

• The number of complete waves that pass a given point in a certain amount of time.

• AKA number of vibrations per second.

• Frequency measured in hertz (Hz).

Speed

• The speed, wavelength, and frequency of a wave are related to each other by a mathematical formula.

• Speed = wavelength x frequency

• Frequency = speed/wavelength

• Wavelength = speed/frequency

WAVE SPEED EQUATION:

Speed

• Waves in different mediums travel at different speeds. However, in a given medium and under the same conditions the speed of the wave is constant.

Exit Slip

• When earthquakes occur, do you think those waves are compressional or transverse waves? Explain your thinking.