Presentation on theme: "What are waves Waves are an important part of the Earth, and not just in the water."— Presentation transcript:
What are waves Waves are an important part of the Earth, and not just in the water.
What is a wave? A wave is a disturbance that transfers energy from place to another place.
What is energy? In science, we define energy as the ability to do work. In the photo Ms. Turner is being moved around by the energy of the wave. When she is being pushed around by the waves the energy in the waves is performing work by moving her around in the surf.
What carries a wave? Many waves require something to carry them. Any substance which carries a wave is a “medium”. Some examples of mediums are: Gases, Air, Liquids, Water, and Solids. Gases, Air, Liquids, Water, and Solids. Waves that require a medium to travel are called “mechanical waves”.
What causes waves? Waves are caused when a source of energy causes a medium to vibrate. A vibration is a repeated back and forth or up and down motion A moving object can transfer energy to a nearby medium to produce a wave. A boat moving through the ocean (a medium) creates a wave.
The three types of waves Waves are classified by how they move. Waves types: Transverse waves. Longitudinal waves. Surface waves.
Transverse waves Transverse waves: move the medium at right angles to the direction of the direction of wave movement. An example would be the waves of a rope. As the medium moves up, the wave moves forward. Lets Draw a Diagram!
Longitudinal waves In longitudinal waves the medium particles move parallel (in the same direction) as the wave is traveling. An example would be a spring. Compressions: areas which the coils in a spring are close together. Rarefactions: areas which the coils of a spring are spread out. Lets draw another diagram!
Surface waves A combination of two mediums working together to produce waves. An example would be water and air combining to produce waves on the ocean. The air is applying energy to the water which alters the wave direction and the intensity of the wave.
Properties of waves Amplitude: is maximum distance the particles of the medium carrying the wave move away from their rest positions. The amplitude is a measure of how much a particle in the medium is disturbed by the wave. Wavelength: the distance between two crests of two waves. Frequency: the number of waves that pass a given point in a certain amount of time. (frequency is measured in hertz, Hz). Speed: how far a wave travels in one unit of time.
Speed, Wavelength, and frequency relationships. Speed = Wavelength x Frequency When you have two quantities of the formula you can calculate the third. Frequency = Wavelength / Speed Wavelength = Speed / Frequency Sample problem: The speed of a wave on a rope is 50 cm/second and the wavelength is 10 cm. What is the frequency? Frequency = 50 cm/s / 10 cm 50 / 10 = 5 (5 per second) or 5 Hz
More sample problems A wave has a wavelength of 5 mm and a frequency of 2 Hz. At what speed does the wave travel? The speed of a wave on a guitar string is 100 m/s and the frequency is 1000 Hz. What is the wavelength of the wave?
Answers to the sample problems A wave has a wavelength of 5 mm and a frequency of 2 Hz. At what speed does the wave travel? Answer: speed = wavelength x Frequency 5(mm) x 2 (Hz) = 10 mm per second The speed of a wave on a guitar string is 100 m/s and the frequency is 1000 Hz. What is the wavelength of the wave? Answer: wavelength = speed/Frequency 100 (m/s) / 1000 (Hz) = 0.1 meter
What are electromagnetic waves? Electromagnetic waves do not require a medium to transfer energy. These waves carry both electrical and magnetic fields. These waves carry a electrical field vertically and the magnetic field is carried horizontally. The energy carried by electromagnetic waves is called electromagnetic radiation. These waves travel at the speed of light.
What does the electromagnetic spectrum look like? The longest wavelengths and the lowest frequencies waves are on the left The shortest wavelengths and the highest frequency waves are on the right. Notice how the light we see as a species is in the middle of the spectrum.
What are the rays of the electromagnetic spectrum Radio waves – used to broadcast both AM and FM stations. These are the longest wavelengths. Microwaves – shorter wavelengths, used in microwave ovens to cook. Infrared rays – used by heat lamps Visible light – the “colors” that we can see. Ultraviolet rays – can cause cancer or damage the eyes. X-rays – used to make images of bones. Gamma rays – these waves have the shortest wavelengths, but carry the greatest amount of energy. Used in cancer treatments (radiation therapy)