phrase difference

Two oscillators that have the same frequency and different phases have a phase difference, and the oscillators are said to be out of phase with each other. The amount by which such oscillators are out of step with each other can be expressed in degrees from 0° to 360°, or in radians from 0 to 2π. If the phase difference is 180 degrees (π radians), then the two oscillators are said to be in antiphase. If two interacting waves meet at a point where they are in antiphase, then destructive interference will occur. It is common for waves of electromagnetic (light, RF), acoustic (sound) or other energy to become superposed in their transmission medium. When that happens, the phase difference determines whether they reinforce or weaken each other. Complete cancellation is possible for waves with equal amplitudes.

A phase difference is analogous to two athletes running around a
race track at the same speed and direction but starting at different
positions on the track. They pass a point at different instants in time.
But the time difference (phase difference) between them is a constant -
same for every pass since they are at the same speed and in the same
direction. If they were at different speeds (different frequencies), the
phase difference is undefined and would only reflect different starting
positions. Technically, phase difference between two entities at
various frequencies is undefined and does not exist.We measure the rotation of the earth in hours, instead of radians.
And therefore time zones are an example of phase differences.

Do you mean "phase" (not phrase) difference? There is no such term as "phrase difference" in physics.

Simply speaking, phase difference is the difference in time or space between two points in a wave. When comparing two (normally identical) waves, it is the difference (in space or in time) between two corresponding points in the two waves. Phase differences are usually expressed in angles.

For example, the crest of a wave and its preceding crest are separated in space by a distance of one wavelength. The two crests are said to be separated by a phase difference of 2.pi radians (since one wavelength corresponds to 2.pi radians in circular measure, where pi = 3.14159....).

The crest of a wave and its preceding trough, however, are separated by [half a wavelength]. Hence, there is a phase difference of [pi] radian.

When comparing two identical waves, if the crest of the first wave meets with the trough of the second wave, the two waves are [half of a wavelength] apart, their phase difference is thus [pi] radians.

Likewise, if the second wave arrives at a point half a period later than the first wave does, the two waves are separated in time by a duration of half a period, or a phase difference of pi radians.

phrase解作句子，片語，如果你係問關於物理，你應該寫phase。phase係物理上解作相位，相位單位多以角度區分，例如交流電一個週期係360度，有兩條交流電其一起始時間比較另一條落後就叫做異相-phase difference，以數學嚟講，sine同cosine就係最佳例子，例sin0係0，但cos0係1，換言之，sine同cosine嘅phase係相差90度。