Describing waves - types of wave

Preparation and Planning

This lesson presumes almost no prior understanding of waves and can be used as an introductory topic to a Scheme of Work or to revise the specific properties of transverse and longitudinal waves. Substantial supporting imagery is attached to each episode. To benefit fully from content, the use of a projector or an interactive whiteboard is advised. All Student Worksheets can be photocopied.

This lesson works well alongside the Defence Dynamics lesson on radio waves and microwaves as part of a larger Unit of Work. Alternatively you may wish to 'mix and match' items to suit your specific needs or to dovetail with existing teaching material.

Understanding of the varied applications of waves for industrial, civilian or military purposes is critical to helping students to understand their importance and role. This lesson interweaves numerous examples of applied use of wave technologies throughout each episode, providing students with considerable contexts for study. Some of these will be more familiar to students than others.

This is a very full lesson and you may wish to remove some activities, or alternatively to use the content across two or more lessons.

About the MOD Topic

A number of military applications of wave technology feature in this lesson. Details on each of these follow:

Security and bomb detection
QinetiQ, the privatised former Defence Evaluation and Research Agency, an MOD department, has identified new means of detecting explosives for use in combating terrorism (with both civilian and military applications).

Just as human bodies emit heat energy, they also naturally emit high-frequency, millimeter-wave energy. And they give off this energy at a different rate than denser materials. Based on that difference, sensors that can detect tiny amounts of millimeter-wave energy emitted by or reflected from objects concealed on a person can reveal a dense object hidden under clothes. Millimetre waves have the ability to penetrate clothing and can be used to detect concealed objects such as guns or knives.

On a larger scale, scanners can be used to see through the canvas sides of a lorry in locations such as the entrance to the Channel Tunnel. The scanner picked up 10,000 illegal immigrants in the back of trucks in its first nine months.

Passive millimetre wave imaging can also be used to image through poor weather. In foggy weather MMW scanners can give a clear outline of the lie of the land, giving strategic advantage in defence applications. This is especially useful for low flying aircraft.

Submarine navigation
Sailors have for centuries been applying rudimentary sonar techniques to assist navigation, using their understanding of the way sound travels through water and air to gauge depth and distance from the shore. Early lighthouses would sound a bell audible through fog, where the echoes indicated its distance to mariners. Underwater bells supported ships' understanding of marine depth along the North American coastline as recently as 1900.

Today's submarines use sophisticated echo-locating devices to determine depth. Using today's technologies supported by a sophisticated understanding of the extent to which sound waves refract under water and the speed at which they move, in saline conditions and at varying depths and temperatures. For submarines, which operate at great depths, it is critical to know for example that increased depth causes the speed of sound underwater to increase.

Radar
Ground penetrating radar is used by the EOD (Explosive Ordnance Division of the Armed Forces) to detect the presence of explosive devices and is occasionally used to detonate them.

Other military applications of radar are more familiar to civilians, including present-day and historical air defence of the UK - providing early warning detection in the event of airborne threat. More sophisticated communications technologies used by all three services today.

The most famous radar detection system in the UK might be considered to be Fylingdales, the MOD's long-range radar station, which forms part of the Ballistic Missile Early Warning System (BMEWS) and Space Surveillance Network (SSN). Fylingdales was the third and last of the BMEWS stations to be built. The first two were built at Thule, Greenland and Clear, Alaska. They operate in the 420-450 MHz frequency range (Federation of American Scientists. Ballistic Missile Early Warning Radar System (BMEWS) at Fylingdales (U) [Internet] Available at: http://tinyurl.com/r2agcr [accessed 25th January 2008]).

2005 earthquake in Pakistan-administered Kashmir
On Saturday 8 October 2005, the Muzaffarabad area of Pakistani-administered Kashmir was hit by a devastating earthquake, recorded at 7.6-7.7 on the Richter scale. As of 8 November, the Pakistani government's official death toll was 73,276 with many more casualties and leaving an estimated 3.3 million homeless.

The UK Government immediately offered assistance. Under the direction of the Department for International Development (DFID), the UK Ministry of Defence made a significant contribution to support the international relief effort through the provision of military personnel, equipment and supplies, under the name Operation MATURIN.

UK Defence contribution included:
Army Commando Engineers from North Devon and Royal Marine Commandos from Plymouth built 73 shelters to replace schools and health centres before the arrival of the harsh winter. All the shelters were built at high altitude and in isolated areas.

Three Chinook helicopters of 27 (EM) Squadron Royal Air Force delivered almost 1,600 tons of aid to the more remote parts of Pakistan administered Kashmir.

A team of British Army and Royal Navy Logistics Officers worked with the United Nations Joint Logistics Centre, helping to plan the co-ordinated delivery of aid to people located in the affected areas of earthquake-hit Pakistan.

Three RAF C-130 Hercules were involved in a six week life saving mission to take essential aid from Europe into Pakistan. They had carried out 22 trips, delivering 292 tons of aid via the NATO airbridge.

A Joint Media Operations Team (JMOT) provided coverage of the UK response in order to heighten overall public awareness of the positive contributions that the UK is making to the relief effort and to help reassure the Pakistan, Indian and Kashmir communities in Britain.

Three medics provided supervision of casualties carried on return CH47 Chinook helicopter sorties, transferring them from landing zones to Islamabad.

A two-man Mobile Air Operations Team (MAOT) was deployed in response to a UN request to survey landing zones to the north of Islamabad, in order to assess the possibility of using a new operating base to ease the aviation congestion difficulties.

Over 23,000 ration packs were sent to Pakistan, including vegetarian and halal packs. All of the ration packs and water were provided to the World Food Programme for distribution.

For more information refer to: http://tinyurl.com/2tsh5m

Further Opportunities for Learning

Invite students to design their own game of Bingo, writing the questions themselves and designing the Bingo Cards. This game might then be run as a revision exercise at the start of a further lesson on waves, e.g. exploring wave properties.

Invite further study of specific wave types e.g. sound waves and their applications in science (including ultrasound) or seismic waves (studying how earthquakes are measured and their causes). Students should also consider the international imperative to share data and knowledge.

Students might study patterns of earthquake prediction, namely the measurement and monitoring of small earthquakes that take place prior to a larger one. Also some of the less scientifically proven methods of prediction e.g. dog bites increasing before an earthquake.

Explore the impact of wavelength, frequency and amplitude on the volume and pitch of a sound wave. www.s-cool.co.uk contains useful interactive diagrams that bring this to life.

If a ripple tank has previously been used in class to demonstrate the nature of various wave types, project work might include further study of their respective properties, prior to this being formally taught. Invite students to set up one experiment only (e.g. explore the diffraction or reflection of a wave) and to summarise their findings. They should be informed that both transverse and longitudinal wave types have the same properties.

Students will be familiar with the Boxing Day 2004 Sumatra - Andaman tsunami, caused by an earthquake below the sea, which killed over 230,000 people. They may wish to debate the role of the international community in sharing knowledge and scientific findings (e.g. earthquake measurement and forecasting systems) to assist less well developed or well-resourced countries.

Student worksheet answers

Download the teachers notes PDF to access the answers for this lesson.