Organ pipe A, with both ends open, has a fundamental frequency of 475 Hz. The third harmonic of organ pipe B, with one end open, has the same frequency as the second harmonic of pipe A. Use 343 m/s for the speed of sound in air. How long are (a) pipe A and (b) pipe B?

The length of organ pipe A is

The length of organ pipe B is  

Explanation:

From the question we are told that

    The fundamental frequency is  

     The speed of sound is  

The fundamental frequency of the organ pipe A  is mathematically represented as

Where L is the length of  organ pipe

   Now  making L the subject

substituting values

The second harmonic frequency of the  organ pipe A is mathematically represented as

The third harmonic frequency of the  organ pipe B is mathematically represented as      

So from the question

So

Making   the subject

substituting values

they should be similar or the same

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