Question

Which of the following conditions is not necessary to observe an interference pattern between two sets of waves?

a. The waves must have the same wavelength.
b. The waves must have a constant phase difference.
c. The waves must have the same amplitude.
d. The waves must have the same frequency.

Answer 1

d. The waves must have the same frequency.

Step-by-step explanation:

We can observe two waves that have interference between them and they create a pattern that can be destructive or constructive, in order for us to see them the waves have to meet three conditions: They need to have the same wavelenght, they must have a constant phase difference, and the same amplitude, otherwise they would interfere with eachother, the only that is not necessary is that they must have the same frequency.

Answer 2

Answer: d. The waves must have the same frequency.

Step-by-step explanation:

Interference is a phenomenon that occurs in all types of waves and consists of the superposition (constructive or destructive) of two or more waves to form a resulting wave of greater, lesser or equal amplitude.

The occurrence of this phenomenon depends fundamentally on the wavelength
`\lambda`, the amplitude and the relative distance between the waves (phase difference).

In this sense, to observe a wave interference pattern from two sources, the following conditions must be met:

-The sources must be coherent, that is, they must maintain a constant phase difference.

-The sources must be monochromatic, that is, they must have exactly the same wavelength.

-The sources must have the same amplitude.

However, it is not necessary that the waves have the same frequency
`f`, the interference pattern will be observed regardless of whether the initial waves have the same frequency or not.

At this point, it is necessary to explain the following:

There is an inversely proportional relationship between frequency and wavelength:

`f=(v)/(\lambda)`

When a wave passes from one medium to another, its wavelength and speed
`v` change, but its frequency does not.