If you were to travel parallel to an infinitely long straight wire with current I at the same velocity as the electrons in the wire at a distance a from the wire,the magnitude of the magnetic field (according to your measuring instruments)would be
A)0.
B) .
C) .
D) .
E) .

Question

If you were to travel parallel to an infinitely long straight wire with current I at the same velocity as the electrons in the wire at a distance a from the wire,the magnitude of the magnetic field (according to your measuring instruments)would be
A)0. 
B) . 
C) . 
D) . 
E) .

Quizplus · Accepted Answer

According to the equation for the magnetic field generated by a long straight wire, the magnitude of the magnetic field depends on the distance from the wire. However, if the observer is traveling at the same velocity as the electrons in the wire parallel to the wire, the observer will not observe any magnetic field. This is due to the fact that the magnetic field is a result of the relative motion between the electrons in the wire and an observer outside the wire. Since the observer is moving at the same velocity as the electrons, there is no relative motion, and thus no magnetic field is observed. Therefore, the correct answer is A: 0.

If You Were to Travel Parallel to an Infinitely Long