S2 1.2 Wave Characteristics

Wave Characteristics

Periodic Waves

• Periodic waves are waves where the pattern of the wave is continuous and repeats after a specific time interval.

• These types of waves are produced by sources that either vibrate or oscillate.

• In the case of a puddle, the raindrops fall on an area of still water and cause a repeated undulation at the point of impact, generating periodic waves that expand outward.

• Let's explore some properties and characteristics of periodic waves through a Phet simulation.

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Parts of a Wave

• Waves start from an equilibrium line.

• The highest points of the wave are called crests and the lowest points are called troughs.

• The distance from two consecutive peaks or troughs is called the wavelength (λ lambda) of the wave.

• Going from equilibrium through a crest and a trough and then back to equilibrium again is called a cycle of a wave.

• The time it takes to go through one cycle is called the period of the wave.

• The height from the equilibrium to the crest is called the amplitude.

Period and Frequency

• The period of a wave is denoted by the capital letter T and is measured in seconds (s), just like when we discussed springs and pendulums.

• The frequency ( ƒ ) of a wave is the number of cycles that are completed in some time period, usually seconds (cycles / second), which is also called hertz (Hz).

• Frequency and period have an inverse relationship with each other: ƒ = 1/T

Period and Frequency

• The period of a wave is denoted by the capital letter T and is measured in seconds (s), just like when we discussed springs and pendulums.

• The frequency ( ƒ ) of a wave is the number of cycles that are completed in some time period, usually seconds (cycles / second), which is also called hertz (Hz).

• Frequency and period have an inverse relationship with each other: ƒ = 1/T

Amplitude and Energy

• Remember that a wave is generated when energy is transferred from a source to its surrounding matter.

• The amplitude of a wave depends on the amount of energy transmitted by the source.

• Waves that have high amplitudes transfer more energy.

• If there's an external damping force acting on the particles, the energy is reduced, and the next particle receives less energy, thereby decreasing the wave's amplitude.

Labelling

Correctly label the parts of the wave.

Drag labels to their correct position on the image

amplitude

crest

equilibrium

trough

cycle

period

peak

distance

frequency

wavelength

Multiple Choice

What will happen to a periodic wave acted upon by an external damping force?

• It will gradually lose energy and decrease in amplitude over time.
• It will remain constant in amplitude over time.
• It will gain energy and increase in amplitude over time.
• It will oscillate at a higher frequency over time.

Multiple Choice

What quantity of a wave does lambda represent?

• amplitude
• frequency
• wavelength
• period

Multiple Choice

A wave takes 0.5 seconds to complete one cycle. Which characteristic of the wave does this description represent?

• Period

• Amplitude
• Frequency
• Wavelength

Multiple Choice

What is the period of a wave with a frequency of 220 Hz?

• 0.5 seconds
• 0.01 seconds
• 0.0045 seconds
• 0.002 seconds

Multiple Choice

The period of a wave is 15 seconds. What is its frequency?

• 1.5 Hz
• 0.15 Hz
• 1/15 Hz
• 15 Hz

Drag and Drop

For a high–amplitude wave to be transmitted a long distance, the source must provide ​

Placeholder

energy and the external damping force must be ​

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.

Drag these tiles and drop them in the correct blank above

high

low

some

pulse

negative

positive

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