Two identical strings, a and b, have nearly the same tension. when they both vibrate in their fundamental resonant modes, there is a beat of 3hz. when string b is tightened slightly, to increase the tension, the beat frequency becomes 6 hz. this means. a) that before and after tightening b has a higher frequency than that of ab) that before and after tightening a has a higher frequency than b. c) that before tightening b had a higher frequency than a, but after tightening, a has a higher frequency than b. d) that before tightening a had a higher frequecy than b, but after tightening. b has a higher frequency than a. e) none of the above.

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

the answer is 12 as i may remember

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365.25 earth days are in the year of a light year