Waves

All waves:

• Transfer energy
• Are created by vibrations
• Need a material to travel through

Mechanical waves:

• Must have a material to travel through

Electromagnetic waves:

• Can travel through a vaccum
• Travel at the speed of light
• Made by vibrating electric and magnetic fields

Transverse waves:

• The vibrations causing the wave are perpendicular to the direction of energy transfer
• All electromagnetic waves are transverse
• Water waves are transverse

Longitudinal waves:

• The vibrations causing the wave are parallel to the direction of energy transfer
• Sound waves are longitudinal

Frequency: Number of waves passing a point in 1 second, measured in Hz. The higher the frequency, the higher the pitch

Amplitude: The maximum distance from the mid position. The higher the amplitude, the louder the sound

Wavelength: The distance between 2 equivalent points on neighbouring waves

Wavespeed ( m/s ) = Frequency ( Hz ) x Length ( m )

OR

Wavespeed ( v ) = Frequency ( f ) x Length 

Reflecting Light:

• i / A. O. I = Angle of incidence
• r / A. O. R = Angle of reflection
• The A.O.R is very similar, if not identical to the A.O.I

Properties of an Image in a PLANE MIRROR:

• Virtual
• Same size & distance from mirror
• Upright, Inline with object

Constructing a ray diagram:

• Draw the image the same distance from the object
• Draw rays from the image to the eye, making sure the rays enter the eye
• Draw the reflected ray

When the light passes from a less dense material-eg. air, to a more dense material- glass, it bends TOWARDS the normal

If the light passes from a more dense to less dense, it bends AWAY from the normal

When white light is dispersed, the different colours refract by different amounts

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Waves spread out when they pass through a narrow enough gap or obstruction

Maximum diffraction: Gap size is the same as the wavelength

• The average human can hear between 20 and 20 000 Hz
• Soundwaves are longitudinal
• Must have a medium to travel through
• The denser the material, the faster the soundwave