Nate wants to see if changing the voltage across a resistor changes the amount of current that flows through it. He plans to run five trials to test a series circuit with one resistor in it.

Which of the following should Nate keep constant in each trial?

A.

the number of trials he runs

B.

the current flowing through the resistor

C.

the voltage across the resistor

D.

the resistance of the resistor

Certain bacteria (such as aquaspirillum magnetotacticum) tend to swim toward the earth’s geographic north pole because they contain tiny particles, called magnetosomes, that are sensitive to a magnetic field. if a transmission line carrying 100 a is laid underwater, at what range of distances would the magnetic field from this line be great enough to interfere with the migration of these bacteria? (assume that a field less than 5% of the earth’s field would have little effect on the bacteria. take the earth’s field to be 5.0 * 10-5 t, and ignore the effects of the seawater.)