Which is a possible displacement-time graph for particle Y?

Answer: Option D

Determine the motion of the particles on transverse wave

Instead of imaging how the particles will move and guess their motion, there is a technique which can help you to determine that.

In addition, when particles are in phase, it means that both particles on the wave have the same velocity and same displacement. It means both have the same speed in the same direction and same distance and direction away from the rest position.

Particles that are out of phase means both are having the same speed but in opposite direction.

Refer to the video below to find out more.

Question 01: 2005/2008 PP P1 Q20/Q18

Answer: Option D

Question 02: 2018 PP P1 Q24

Answer: Option B

Graphs of Transverse Wave – E.g. Water waves

Refer to the Graphs of Sound Waves here

Graphs of Sound Waves

Waves

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Slinky Coil – Interesting Tricks and demonstrations of Transverse and Longitudinal Waves

Slink coil is usually used to demonstrate the two types of waves – transverse and longitudinal waves. But remember that when you are asked to state an example of each wave, do not quote slinky coil.

View the videos below to know more about the two types of waves.

Using Slinky Coil to demonstrate Transverse and Longitudinal Waves

Though slinky coil is commonly used to demonstrate transverse and longitudinal waves, you must not quote it as an example for either of the waves.

• Transverse waves are waves in which the direction of the wave is perpendicular to the direction of the vibration of the particles. Examples are light wave, water wave or all the waves in the electromagnetic spectrum (which light is one of the waves.
• Longitudinal waves are waves in which the direction of the wave is parallel to the direction of the vibration of the particles.  Example is sound wave.

Transverse Waves (slinky coil)

Longitudinal Waves (slinky coil)

Transverse Waves Animation

Longitudinal Waves Animation

Click here to see the simulations of transverse and longitudinal waves.

Electromagnetic Spectrum – updated

One amendment done – Mobile communication should be using microwaves.

Waves Summary

 

Click here to view the simulations transverse and longitudinal waves

Students are confused when they need to visualise what is the direction of the particles the next moment of the wave. There is a simpler way solve such question.

To know what is the motion of the particles as a transverse wave passes through, click to view the question and the video tutorial.

Click here to view of a question asked on rope wave – how should you move your hand to create different waves.

Click here to view another example on graphs

Click here to know more about wavefronts created in a ripple tank.

 

 

Waves Summary – Amended

Amendments to the Sound information – added info when sound travels from less dense (air) to denser medium (water or solid)

Transverse Wave – Convert to Displacement-Time Graph

Transverse Wave – Position of x at t = 3s

General Wave Properties – Rope Wave

As Pie is vibrating the rope up and down as shown, creating a transverse wave.

With only vertical displacement (no forward displacement/force is applied to the rope), the speed of the wave is constant.

Since V = fλ, frequency (f) is inversely proportional to wavelength (λ).

Consider the following questions:

a) If Pie wishes to double the frequency of the wave, how should he move his hands?
He should double the speed in which he moves his hands up and down to double the frequency.

b) When the frequency is doubled, what can you say about the wavelength?

Wavelength will be halved. (recall wavelength is inversely proportional to frequency)

c) If Pie wants the waves to be closer, how should he move his hands?

He should increase the speed in which he moves his hands up and down, hence increasing the frquency.

d) If Pie wants to achieve a frequency of 2 Hz, how should he move his hands in order to achieve that?

He should move his hands down and up 2 times (2 complete waves) in 1 second to achieve frequency of 2 Hz.

e) If Pie wants to have a higher amplitude, how should he moves his hands?

He should increase the vertical displacement of the hands to achieve a higher amplitude.

Transverse Waves and Longitudinal Waves

Transverse waves are waves in which the direction of the wave is perpendicular to thedirection of the vibration.
e.g Light, water, and any waves in the electromagnetic spectrum

Longitudinal waves are waves in which the direction of the wave is parallel to the direction of the vibration.
e.g Sound

Wave equation: V = fλ 
From the rope videos, with only vertical displacement, speed of wave is constant.
Hence frequency is inversely proportional to wavelength. [f increases, λ decreases, and vice versa]

 

Transverse Waves and Longitudinal Waves

Transverse waves are waves in which the direction of the wave is perpendicular to thedirection of the vibration.
e.g Light, water, and any waves in the electromagnetic spectrum

Longitudinal waves are waves in which the direction of the wave is parallel to the direction of the vibration.
e.g Sound

Wave equation: V = fλ 
From the rope videos, with only vertical displacement, speed of wave is constant.
Hence frequency is inversely proportional to wavelength. [f increases, λ decreases, and vice versa]