Interactions of waves

Ways Waves Interact Reflection Refraction Diffraction Interference Constructive Destructive Standing Waves

Reflection the turning back of a wave when it reaches the boundary of the medium through which it is traveling

Law of Reflection the angle of incidence is equal to the angle of reflection

perpendicular

Examples of reflection Mirror Echo Ball against a wall

Reflection When an object or wave hits a surface through which it cannot pass, it bounces back.

Refraction the bending of a wave as it passes obliquely from one medium into another at a different speed For refraction to occur, the wave must change speed and must enter the new medium at an oblique angle.

Refraction When a wave moves from one medium into another medium, at an angle, it changes speed as it enters the second medium which causes it to bend. The bending of waves due to a change in speed is called refraction.

Change in Medium Animation

The greater the change in speed, the more the wave bends. Light goes air to water, slows and bends toward normal.

Light goes water to air, speeds up and bends away from normal.

Rainbows Light passing through water causes light to refract. The colors , being different wavelengths, refract different amounts. It is always ROYGBIV.

Diffraction the spreading of a wave around a barrier or through an opening

Diffraction When a wave passes a barrier, or moves through a hole in a barrier, it bends and spreads out.

Diffraction Sound being heard from around a corner and light being seen around a corner are examples of diffraction. Diffraction depends on wavelength and the size of the hole or bend. Matter cannot be in the same space at the same time but energy can! No! For real?

Interference Interference is the overlapping of two or more energy waves. Cool!

What is wave interference? Waves interfere in one of two ways: Constructive Interference and Destructive Interference.

Constructive interference Constructive interference occurs whenever two waves combine to make a wave with a larger amplitude.

Constructive Interference Let’s consider two waves moving towards each other, both having a positive upward amplitude. What will happen when they meet?

Constructive Interference They will ADD together to produce a greater amplitude. This is known as CONSTRUCTIVE INTERFERENCE.

Destructive interference Destructive interference when the amplitudes of two waves combine producing a smaller amplitude.

Destructive Interference Now let’s consider the opposite, two waves moving towards each other, one having a positive (upward) and one a negative (downward) amplitude. What will happen when they meet?

Destructive Interference This time when they add together they will produce a smaller amplitude. This is know as DESTRUCTIVE INTERFERENCE.

Types of Interference Constructive results in a larger amplitude Destructive results in a smaller amplitude

Check Your Understanding Which points will produce constructive interference and which will produce destructive interference? Constructive G, J, M, N Destructive H, I, K, L, O

A standing wave is the result of two waves of the same wavelength, frequency, and amplitude traveling in opposite directions through the same medium.