# Evan's Space

## Wonders of Physics ## 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.

## Electromagnetic Spectrum – updated

One amendment done – Mobile communication should be using microwaves. ## Waves Summary 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.   ## 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]