Properties of Waves By Anil Hassan Olu Wave

Properties of Waves By: Anil, Hassan, Olu

Wave Reflection • A change in direction that a wave experiences when it bounces off of a barrier between two kinds of media. • Reflection from a rigid obstacle, usually referred to as fixed-end reflection, the pulse is inverted. A crest is reflected as a trough and trough is reflected as a crest. If the reflection occurs from a free end , where the medium is free to move, there is no inversion, crest are reflected as crests and troughs as troughs. In both there is no change in wavelength or frequency. Nor any change in speed of pulse since medium is the same. • I learned that in a fixed-end reflection the pulse is inverted because the medium is not free to move. Whereas in a free end reflection the pulse is not inverted because the medium is free to move.

Wave Reflection • I learnt that in the reflection of a wave, the angle of incidence is equal to the angle of refection. • I learnt that the reflectivity of a surface material is the fraction of energy of the oncoming wave that is reflected by it. • I learnt that the angle of incidence is the angle between the direction of a motion of the oncoming wave and perpendicular to a reflecting surface, while the angle of reflection is the angle between the direction of motion of the reflected and a perpendicular.

Wave Transmission • At the boundary between two medias, the speed and wavelength change, and some reflection occurs. This is called partial reflection because some of the energy is transmitted into the new medium and some is reflected back into the original medium. • When a wave travels from a slow medium to a fast medium, the fast medium acts like a “freeend” reflection. No inversion occurs in either the reflected or transmitted wave, but there are changes in the wavelength and in the speed of the transmitted wave. • When a wave travels from a fast medium to a slow medium, the medium acts as a rigid obstacle, and the reflected wave is inverted. However, the transmitted wave is not inverted. • I learned that when a wave travels from a slow medium to a fast medium, the fast medium acts like a free-end reflection. Whereas when a wave travels from a fast medium to a slow medium the medium acts as a rigid obstacle and the reflected wave is inverted.

Interference • Wave interference occurs when two waves act simultaneously on the same particles of a medium. There are two types of interference: constructive and destructive. • Destructive interference occurs when a crest meets a trough. If the crest and trough have equal amplitude and shape, their amplitudes cancel each other for an instant. Then the crest and trough continue in their original directions. • Constructive interference occurs when pulses build each other up, resulting in the medium having a larger amplitude. • The principle of superposition is at any point the resulting amplitude of two interfering waves is the algebraic sum of the displacements of the individual waves. • A node is a point at which lines or pathways intersect or branch; a central or connecting point. • I learned when in phase waves are added the pulses build each other up, resulting in the medium to have a larger amplitude. Whereas in a out phase wave the crest and trough have equal amplitude and shape, so their amplitudes cancel each other for an instant.

Doppler Effect • An increase or decrease in the frequency of sound, light, or other waves as the source and observer move toward or away from each other. The effect causes the sudden change in pitch noticeable in a passing siren, as well as the redshift seen by astronomers. • When a police vehicle or emergency vehicle is travelling towards you on the highway, as the vehicle approaches with its siren blasting, the sirens frequency is high(sounds approaching) and as the emergency vehicle passes by the frequency slowly decreases (sounds departing). • I learned as a sound approaches you the frequency is higher and as the sound departs the frequency slowly decreases.

Standing Waves • A standing wave is a vibrational pattern created within a medium when the vibrational frequency of the source causes reflected waves from one end of the medium to interfere with the incident waves from the source. • As the frequency on the string has a constant increase of 25 Hz, the number of harmonics increases by one. Therefore at 50 Hz the number of harmonics is represented by x+1 and at 75 Hz represented by x+2 where x equals 1. Also as the frequency increases the wavelength decreases.

Bibliography • Acoustics and Vibration Animations. (n. d. ). Reflection of Wave Pulses from Boundaries. Retrieved October 13, 2014, from http: //www. acs. psu. edu/drussell/Demos/reflect. html • Travelling waves, superposition, reflection and transmission. (n. d. ). Waves in a string: reflections and superposition. From Physclips. Retrieved October 13, 2014, from http: //www. animations. physics. unsw. edu. au/jw/waves_superposition_reflection. htm#reflections • Wave Interference 2. (n. d. ). Physics, Math Home. Retrieved October 12, 2014, from http: //zonalandeducation. com/mstm/physics/waves/interference/wave. Interference 2/Wave. Inter ference 2. html • Wave Reflection at an Impedance Discontinuity. (n. d. ). Wave Reflection at an Impedance Discontinuity. Retrieved October 13, 2014, from http: //physics. usask. ca/~hirose/ep 225/animation/reflection/anim-reflection. htm • Wave reflection. • http: //www. physicsclassroom. com/class/waves/Lesson-3/Reflection, -Refraction, -and-Diffraction • Refection of waves pulses from boundaries • http: //www. acs. psu. edu/drussell/Demos/reflect. html • Reflection of waves • http: //hyperphysics. phy-astr. gsu. edu/hbase/sound/reflec. html