If the speed of a wave increases but the frequency remains the same, what must be true of its wavelength?
the wavelength will decrease.
the wavelength will fluctuate wildly.
the wavelength will increase.
the wavelength will stay the same.

If the speed of a wave increases but the frequency remains the same, the wavelength will increase.

Explanation:

V = f λ

V is the speed

F is the frequency  

F λ is wavelength  

If we look at the above equation, it can be deduced that frequency and wavelength are inversely proportional to one another.  

Frequency is the number of cycles made per second. Wavelength is the distance between two crests or troughs.

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explanation:

the correct answer is 2 and 4