An airliner at take off has a sound power of approximately 5.0 x 10 'W. An airport operator is 30 meters away. Calculate: the intensity and the sound level perceived by the operator; the intensity and the sound level at a distance of 2000 m near a built-up area. Is the value found within the legal limits (<80 dB)?

Electromagnetic induction. a coil of wire contains n turns and has an electrical resistance r. the radius of each turn is a. initially, inside the coil there exists a uniform magnetic field of magnitude b0 parallel to the axis of the coil. the magnetic field is then reduced slowly. the current induced in the coil is i. how long does it take for the magnitude of the uniform field to drop to zero?