Theories and laws.

• how are they alike?

• how are they different?

• can you explain why scientific theories will change over time?

• give an example of a scientific theory that has changed. did it become a scientific law, become obsolete, or become part of a revised scientific theory?

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?