What are the first three harmonics of a note produced on a 32.0 cm long violin string if waves on this string have a speed of 280.0 m/s? ___ Hz
___Hz
___Hz

The first harmonics are the fundamental, the first overtone, and the second overtone,

For a string fixed at both ends you have:

N-A-N            F/2

N-A-N-A-N     F

N-A-N-A-N-A-N    3 F/2        each harmonic increases by F/2

Where N are the anti-nodes and A the antinodes

N-A-N-A-N    represents 1 wavelength for string fixed at both ends

So 1 wavelength is 64 cm

280 m/s = F * .64 m       and F = 437.5 Hz       (second harmonic)

First harmonic = F/2 = 218.75 / sec

Third harmonic = 3 F / 2 = 656.25 /sec

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia