Physics Revisit: Waves

Physics Revisit: Waves

Physics Revisit: Waves 620 324 School Tutoring

The wave is a new concept for most students. When there is only one wave, you only need to worry about four things: wavelength, frequency, amplitude and velocity.

Wavelength is a distance of one complete cycle of a wave.
Frequency is number of waves repeat in one second.
Amplitude is a measure of height of wave’s oscillations.
Velocity is a distance a wave travels in one second.

In sound velocity is fixed, 343m/s in normal temperature. Frequency determines pitch of the sound. The amplitude determines how loud the sound is.
In light, velocity is fixed, 3 x10^8m/s. In light, wavelength determines colour of the light. Lights with high wavelength have bright colours while lights with low wavelength have dark colours. If wavelength is really low, it can harm people’s skin.

The formula for the wavelength, frequency and velocity is
Velocity = wavelength x frequency.
As you can see, for sound and light, velocity is fixed, so wavelength and frequency is inversely proportional to each other.

When there are two wave meeting, you have to consider node and anti-node. When two waves meet, it produces new wave. Wave has Crest and trough. Crest is a positive part and trough is negative part of the wave.

There are two waves with name A and B. If crest of Wave A and crest of Wave B meets, the wave becomes stronger by adding the positives. If trough of Wave A and trough of Wave B meets, the wave becomes stronger by adding the negatives. However, if trough and crest meet, the wave becomes weaker by adding a positive and a negative.

The point where trough and crest meet is called node point.
The point where trough and trough meet or crest and crest meet are called anti-node.

If the wavelength of wave A is 2m, and the wave A is starting from point S1. The crest happens every even distance. 2, 4, 6, 8m… are the line of crest. Then you can get line of trough by adding half of the wavelength to line of crests. Therefore line of trough of wave A would happen every odd number distance. 1,3 5, 7m… are the line of trough.

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