Chapter 11 Section 3
Introduction What happens to a ball when it hits the wall? What happens to a ball when it hits the wall? How do you think a ball might travel differently in water? How do you think a ball might travel differently in water? Today you will learn how a wave behaves when it hits something or travels through different media! Today you will learn how a wave behaves when it hits something or travels through different media!
Behavior of Waves Reflection: Reflection: Occurs when a wave strikes an object and bounces off of it Occurs when a wave strikes an object and bounces off of it All waves---including sound, water, light waves can be reflected All waves---including sound, water, light waves can be reflected Ex: Seeing your self in a mirror, hearing echoing down an empty hallway etc Ex: Seeing your self in a mirror, hearing echoing down an empty hallway etc What are some other ways you think waves are reflected? What are some other ways you think waves are reflected?
Behavior of Waves Law of Reflection Law of Reflection According the law of reflection the angle of incidence is equal to the angle of reflection According the law of reflection the angle of incidence is equal to the angle of reflection For example: when you throw a bounce pass in basketball, the angle between the ball’s direction and the normal to the floor is the same before and after it bounces For example: when you throw a bounce pass in basketball, the angle between the ball’s direction and the normal to the floor is the same before and after it bounces
Incidence Beam Reflection Beam
Behavior of Waves Refraction Refraction Is the bending of a wave caused by a change in its speed as it moves from on medium to another. The greater the speed change, the more the wave bends Is the bending of a wave caused by a change in its speed as it moves from on medium to another. The greater the speed change, the more the wave bends Ex: Pencil in water cup, swimming Ex: Pencil in water cup, swimming
Behavior of Waves Diffraction Diffraction Occurs when an object causes a wave to change direction and bend around it Occurs when an object causes a wave to change direction and bend around it Ex: waves hitting an island Ex: waves hitting an island
Interference Definition Definition When two or more waves overlap and combine to form a new wave. When two or more waves overlap and combine to form a new wave. Two types: Two types: Constructive interference Constructive interference Destructive interference Destructive interference
Constructive Interference Happens when the crests of two or more transverse waves arrive at the same place and time and over lap (they add together) Happens when the crests of two or more transverse waves arrive at the same place and time and over lap (they add together) The amplitude of the new wave is equal to the sum of the amplitudes of the original waves The amplitude of the new wave is equal to the sum of the amplitudes of the original waves Also occurs when the compressions of different compressional waves overlap Also occurs when the compressions of different compressional waves overlap Produces a louder sound Produces a louder sound
Destructive interference When the crests of one transverse wave meet the troughs of another transverse wave (they subtract from each other) When the crests of one transverse wave meet the troughs of another transverse wave (they subtract from each other) Compressional waves D.I. occurs when the compression (more dense) of one wave overlaps with rarefraction (less dense) of another wave producing a reduced amplitude Compressional waves D.I. occurs when the compression (more dense) of one wave overlaps with rarefraction (less dense) of another wave producing a reduced amplitude Decrease in loudness Decrease in loudness Ear protectors accomplish this Ear protectors accomplish this
Resonance The ability of an object to vibrate by absorbing energy at its natural frequency The ability of an object to vibrate by absorbing energy at its natural frequency Size and shape of an object can change its resonance Size and shape of an object can change its resonance
Polarization—CANT BE FOUND IN BOOK!! Process of aligning the direction of a transverse wave’s vibrations Process of aligning the direction of a transverse wave’s vibrations Ex. Polarized sunglasses commonly used for fishing Ex. Polarized sunglasses commonly used for fishing