Home » 國際課程 » A-level課程 » Details

CIE A Level Physics復習筆記7.1.5 Transverse & Longitudinal Waves

Category: A-level課程, 教材筆記, 福利干貨 Date: 2022年8月16日下午3:00

Properties of Transverse & Longitudinal Waves

In mechanical waves, particles oscillate about fixed points
The direction of oscillations with regards to the direction of wave travel determine what type of wave it is

Transverse waves

A transverse wave is one where the particles oscillate?perpendicular?to the direction of the wave travel (and energy transfer)
Transverse waves show areas of?crests?(peaks) and?troughs

7.1.2.1-Transverse-wave-diagram

Diagram of a transverse wave

Examples of transverse waves are:
- Electromagnetic waves e.g. radio, visible light, UV
- Vibrations on a guitar string
These can be shown on a rope
Transverse waves?can?be polarised

Longitudinal waves

A longitudinal wave is one where the particles oscillate?parallel?to the direction of the wave travel (and energy transfer)
Longitudinal waves show areas of?compressions?and?rarefactions

7.1.2.1-Longitudinal-wave-diagram

Diagram of a longitudinal wave

Examples of longitudinal waves are:
- Sound waves
- Ultrasound waves
These can be shown on a slinky spring
Longitudinal waves?cannot?be polarised
You will have learned how to analyse the properties of a wave, such as amplitude and wavelength, in “General Wave Properties”
The diagram below shows the equivalent of a wavelength on a longitudinal wave

7.1.2.1-Wavelength-on-transverse-and-longitudinal-waves

Wavelength shown on a longitudinal wave

Exam Tip

The definition of transverse and longitudinal waves are often asked as exam questions, make sure to remember these definitions by heart!

Graphical Representations of Transverse & Longitudinal Waves

Worked Example

The graph shows how the displacement of a particle in a wave varies with time. WE-Transverse-and-Longitudinal-wave-question-image

Which statement is correct?

A.?The wave has an amplitude of 2 cm and could be either transverse or longitudinal.

B.?The wave has an amplitude of 2 cm and has a time period of 6 s.

C.?The wave has an amplitude of 4 cm and has a time period of 4 s.

D.?The wave has an amplitude of 4 cm and must be transverse.

ANSWER:? ?A

7.1.2.1-Worked-example-transverse-and-longitudinal-wave-2

Exam Tip

Both transverse and longitudinal waves can look like transverse waves when plotted on a graph - make sure you read the question and look for whether the wave travels?parallel?(longitudinal) or?perpendicular?(transverse) to the direction of travel to confirm which type of wave it is.

轉載自savemyexams