What are beats? a. periodic fluctuations in the velocity of sound waves b. periodic fluctuations in the wavelength of sound waves c. periodic fluctuations in the intensity of sound waves d. periodic fluctuations in the frequency of sound waves

D. periodic fluctuations in the frequency of sound waves

Explanation:

Beat is referred to the phenomena that occurs when to sound waves interfer with each other and they have different frequencies.

This difference is what creates a beating, wich in sound waves manifest as high and low sounds, this as a result of the oscilating frequency .

i dont know but

explanation:

whoever your teacher is, deserves a raise for using pokemon as an example

a.metals can become magnetic if they have many spinning electrons that create magnetic fields.d.only some metals are attracted by magnets; these metals are called ferromagnetic.

d.wrapping an insulated wire around a metal with ferromagnetic properties and applying an electric current.