Why is it important to learn about waves? Waves are all around us. When fault zones move potential energy is changed to kinetic energy. This energy then travels through earth and water via oscillating waves. These waves can cause destruction to surrounding societies. The sound of a guitarist's strum carries waves to our ears. Audio speakers translate electrical signals into physical vibrations to create sound waves. Waves help students contact their friend's cell phone while you may be teaching a class.
Waves are types of oscillations traveling from one place to the next. Waves propagate through various substances. Water waves and sound waves are both produced by some sort of oscillation. The water wave is a common known wave that most students can see. This is a good starting point to introduce the parts of a wave. Water waves are created by oscillations of water molecules. As water waves pass through an ocean, water molecules oscillate up and down and back and forth. Ocean waves are transverse waves. These waves are perpendicular to the direction of the wave. This means that the water wave is moving at a right angle to direction of the wave; as a water wave progresses from east to west for example, the wave itself moves up and down,
Activity 1 Wave Observations In Our Environment
I will begin my unit by asking our class to exit the school and stand on the corner of a busy street. We will consider how we are affected by waves. Students may respond with light waves: stop lights, the suns illuminations, sound waves: the sound of car engines combusting, horns, and people talking to each other, electrical waves flowing through wires, water waves rippling in a puddle and invisible waves from radio, TV and cell phone transmissions through the air around us. This activity will reintroduce the idea of a wave.
One type of wave that will be constantly changing is the sound wave. Students will be able to notices changes in sound from one second to the next. Ask students what type of changes they observe with sounds they hear. Students will be able to distinguish between different volumes and pitches. Some sounds will be soothing while others may be harsh. All these observation will be beneficial to use as examples when you delve further into the properties of sound waves later on in the unit.
Activity 2 Measurements of Water Waves
The properties of a wave will be introduced with a trip to the beach. Students will measure the height, amplitude, wavelength and period of the water waves. Data collectors cannot be water shy and a good pair of rubber boots will be necessary. Necessary materials will include a measuring tape, timer and a long wooden stake. Students will begin by measuring the height of the wave. The height is the vertical distance separating the high point on the crest from the low point of the trough. Students will then divide this value by two to get the amplitude of the wave. The wavelength will be measured by finding the horizontal distance between the crest of one wave to the crest of the next. The period of the wave will be the time it takes one two successive crests to pass a stationary point. The speed of the wave can then be calculated by dividing the wavelength by the period. Students will have to be quick in their observations. Increasing the number of trials, and finding the mean of the values, will generate accuracy in data and excitement for a rather mundane topic. This activity will provide a tactile body kinesthetic representation of waves and how waves are measured.