The drawing shows two loudspeakers 1 metre apart. Both speakers are connected to the same signal generator, so both speakers are producing exactly the same sound waves. If you walk along line A–B you will hear the sound changing from loud to quiet and back again. Explain why the loudness of the sound changes as you walk along line A-B.

Currents in dc transmission lines can be 100 a or higher. some people are concerned that the electromagnetic fields from such lines near their homes could pose health dangers. for a line that has current 150 a and a height of 8.0 m above the ground, what magnetic field does the line produce at ground level? express your answer in teslas and as a percentage of the earth’s magnetic field, which is 0.50 g. is this value cause for worry?