# Science Notecards #4 (Unit 4: Waves, Light and Sound)

## 20 terms · 8th grade science vocabulary

### Mechanical Wave

waves that use matter to transfer energy

### Electromagnetic Wave

a wave that travels through empty space or through matter; produced by charged particles that are in motion

### Transverse Wave

the wav energy cause the matter in the medium to move up and down or back and forth at right angles to the direction the wave travels

### Longitudinal (compressional) wave

matter in the medium moves forward and backward along the same direction that the wave travels

### Medium

the matter through which a mechanical wave travels

### Hertz

the unit of frequency is the number of wavelengths per seconds

### Compression

the group of molecules that are close together

### Rarefaction

a group of molecules that are farther apart

### Wavelength

the distance from the top of one crest to the top of the next crest, or from the bottom of one trough to the bottom of the next trough

### Amplitude

one-half the distance between a crest and a trough

### Wave Height

the vertical distance from the crest to the trough

### Resting Point

point on a wave where no matter is disturbed

### Crest

the highest point in a wave

### Trough

the lowest point in a wave

### Wave Speed

frequency (times) x wavelength

### Reflection

occurs when a wave strikes an object or surface and bounces off

### Refraction

the bending of a wave as it moves from one medium into another

### Diffraction

is the bending of waves around a barrier

### Interference

the ability of two waves to combine and form a new wave when they overlap

### Electromagnetic Spectrum

the wide range of electromagnetic waves with different frequencies and wavelengths