#### What is being taught lesson by lesson:

• Look at the two types of waves, longitudinal and transverse. Link them to common types such as sound and light.
• Define and measure amplitude, wavelength, frequency, period, peak, trough. The relationship between period and frequency – f=1/p and p=1/f. Calculate wave speed using v=f λ.
• Look at the reflection from mirrors and curved mirrors. Construct ray diagrams.
• For refraction, ray diagrams are used to show the change in direction of waves when the density of the medium changes.
• When we use refraction and how it works for those applications.
• Practice on calculations concerning waves
• Light and colour. Things that we take for granted, this lesson explains them.
• This lesson is all about lenses. It shows how they work and links to refraction and how light has its speed altered.
• Understanding transparent and opaque materials
• The electromagnetic spectrum. All of the parts, their uses, their dangers and the relationship between speed, frequency and wavelength.
• Ultrasound and seismic waves.

#### Key Terms for this topic (Tier 3 vocabulary)

Transverse – longitudinal – displacement – amplitude – wavelength – frequency – period – reflection – refraction – diffraction – angle of incidence – wavefront – electromagnetic spectrum – ionosphere – total internal reflection.

Waves

Are you ready for your assessment in this topic? Try out this simple quiz.

#### What everyone needs to know:

The two types of waves are: transverse (up and down like the sea) and longitudinal (areas of compression and rarefaction like sound in air). You need to be able to describe the differences and similarities. Make sure that you know that air particles to not travel from a person’s mouth to your ear when you hear them and that ripples in a pond move from the centre to the edge but the water molecules simply bob up and down.

Check that you can identify and label: Amplitude, wavelength, peaks, troughs. You need to be able to calculate frequency (1/time period) and use:

v=f λ

Wave velocity = frequency x wavelength

Make sure that you can describe how to test the speed of a sound wave as well as the speed of waves on water.

Electromagnetic waves are transverse waves that have a spectrum which you need to learn (radio waves to Gamma rays). Make sure that you know the uses and dangers of each type.

Use ray diagrams to show refraction when two different mediums meet (air to glass for example).

Required practical 20 – Use equipment, such as a ripple tank to make observations and measurements of waves. Calculate wavelength and speed.

Required practical 21 – Investigate the effect on heating through infrared radiation when changing the surface of a container.

#### Extra topics needed for the Higher papers:

Describe how different substances absorb, transmit, reflect and refract electromagnetic waves. refraction is caused by the waves changing speed in different mediums.

Radio waves can be produced by oscillations in electrical circuits. When they are absorbed, they can produce an alternating current of the same frequency.