A stereo speaker produces a pure "A" tone, with a frequency of 220.0 Hz. What is the period of the sound wave produced by the speaker?

T=

What is the wavelength water of the same sound wave as it enters some water, where it has a speed of about 1480 m/s?

λwater=

What is the wavelength air of this sound wave as it travels through air with a speed of about 341 m/s?

λair=

the higher the current the higher the mag field around it the higher the influence on the compass

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.

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

myth. it was once thought that animals, including cats and dogs, could only see in black and white. however, scientists have proven this to be a myth. in all animals, including humans, the perception of colour is determined by the presence of cells in the eye called cone photoreceptors.