# wavelength

## defining wavelength

Wavelength is one way of measuring the size of waves. It is the distance between two corresponding points on adjacent waves, and it is usually measured in meters. How it is measured is a little different for transverse and longitudinal waves. In a transverse wave, particles of the medium vibrate up and down at right angles to the direction that the wave travels. The wavelength of a transverse wave can be measured as the distance between two adjacent crests, or high points, as shown in the Figure 1.1. In a longitudinal wave, particles of matter vibrate back and forth in the same direction that the wave travels. The wavelength of a longitudinal wave can be measured as the distance between two adjacent compressions, as shown in the Figure 1.2. Compressions are the places where particles of the medium crowd close together as the energy of the wave passes through.

## wavelength and wave energy

The wavelength of a wave is related to the waves energy. Short-wavelength waves have more energy than long- wavelength waves of the same amplitude. (Amplitude is a measure of how far particles of the medium move up and down or back and forth when a wave passes through them.) You can see examples of transverse waves with shorter and longer wavelengths in the Figure 1.3. A: Violet light has the greatest energy because it has the shortest wavelength.

## instructional diagrams

No diagram descriptions associated with this lesson

## questions

the wavelength of visible light determines its color.

``````-->  a. true

b. false
``````

wavelength usually is measured in meters.

``````-->  a. true

b. false
``````

in a transverse wave, wavelength can be measured as the distance between

``````-->  a) two adjacent crests.

b) a crest and the adjacent trough.

c) a crest and the resting position.

d) none of the above
``````

in a longitudinal wave, wavelength can be measured as the distance between

``````a) two adjacent compressions.

b) two adjacent rarefactions.

c) a compression and the adjacent rarefaction.

-->  d) two of the above
``````

for waves of the same amplitude, shorter wavelength waves have less energy than longer wavelength waves.

``````a. true

-->  b. false
``````

which color of visible light has the longest wavelength?

``````-->  a) red

b) orange

c) yellow

d) green
``````

which color of visible light has the most energy?

``````a) red

b) green

c) blue

-->  d) violet
``````

## diagram questions

No diagram questions associated with this lesson