Kate gathered three boxes of the same size made of different materials: glass, clear plastic, and aluminum painted black. she placed them on a windowsill in the sun for an hour and then measured the warmth of the air in each box. in this experiment, the warmth of the air is a(n) a independent variable b constant c control d dependent variable

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?