Sound and Light Waves Sound Light

Waves Energy is carried from one place to another by waves A longitudinal wave moves through a medium by particles being moved apart and pushed together. A transverse wave moves through a medium by particles moving perpendicular to the direction of motion. A photon is a small bundle of light energy that makes up light.

Longitudinal Waves

Transverse Waves

Photon

How Sound is Produced Matter must vibrate, move back and forth, for sound to be produced. As matter vibrates, the matter causes the air molecules to vibrate also. Sound travels only through particles, not empty space. When an object is more dense, sound waves move faster and with greater intensity.

Sounds Intensity – the strength of a sound Decibel – a unit that measures the intensity of sound Volume – the loudness of a sound

Sounds Pitch – how high or low a sound is Frequency – the number of vibrations per second of a sound wave Cycle – the complete back-and-forth motion of a vibration Hertz (Hz) – the unit used to measure frequency of a sound; one Hertz equals one cycle per second

Pitch and Frequency

Speed of Sound Speed of sound through air = 346 m/s at a temperature of 25 °C As temperature increases, molecules move farther apart. Therefore, speed of sound slows. As density increases, molecules are closer together. Therefore, the speed of sound increases.

Speed of Sound

Speed = (frequency)(wavelength) s =  What is the frequency of a wavelength if the speed of the wave is 14 m/s and the wavelength is 2 m? s =  14 m/s =  (2 m)  m/s / 2 m  = 7 Hz

Speed of Sound What is the wavelength of a wave that has a speed of 35 m/s and a frequency of 5 Hz? What is the speed of a wave that has a wavelength of 8 m and a frequency of 6 Hz?

Properties of Sound Reflect – to bounce back Echo – A sound that is reflected to its source Sonar – A method of using sound to measure distances under water

Properties of Sound Ultrasound – a technique that uses sound waves to study organs inside the human body

Properties of Sound Doppler effect - the apparent change in frequency of a wave As the object moves closer, the sound seems higher and louder. As the object moves away, the sound seems lower and quieter.

Doppler Effect

Light A form of energy that can be seen Photon – small bundles of energy that make up light Light has properties that suggest it is a particle and a wave.

Light Visible spectrum – the band of colors that make up white light; the colors in a rainbow Prism – a clear piece of glass or plastic that is shaped like a triangle; it can be used to separate white light

Light Properties Image – a copy or likeness Plane mirror – a flat, smooth mirror

Light Properties Concave mirror – a mirror that curves in at the middle Focal point – the point where reflected light rays from a concave mirror come together in from of the mirror

Light Properties Convex mirror – a mirror that curves outward at the middle

Light Properties Refraction – the bending of a light wave as it moves from one material to another Lens – a curved piece of clear material that refracts light waves Concave lens – a lens that is thin in the middle and thick at the edges Convex lens – a lens that is thick in the middle and thin at the edges

Light Properties

Eye Sight Nearsightedness – able to see objects that are close up clearly Farsightedness – able to see objects at a distance clearly

Light Properties Diffraction – the bending and spreading out of a wave around an object

Light Properties Interference – different intensities of waves because of addition or subtraction of a wave Blocking certain waves but allowing other waves to pass through a vertical slit in an object occurs because of polarization