Question about solenoid.(concept)?

2016-08-05 6:27 am

Since it is difficult to place any apparatus inside such a small solenoid (radius 1cm) to measure the field, the student decides to measure the field at one end. Do you think that the value he obtains is larger or smaller than the theoretical value inside the solenoid? (Hint: Consider two identical solenoids "in series")

回答 (1)

天同

2016-08-05 8:42 am

✔ 最佳答案

It is smaller.

When measured at the middle of the solenoid, you an imagine that magnetic field contribution comes from two solenoids, one to the left and one to the right of the measuring point, with length of each of the solenoid half of that of the original one (L say). Thus the farthest end of the solenoid from the measuring point is L/2.

With the measuring point placed at the end of a solenoid of length L, the farthest end is at distance L from it. It is obvious that magnetic field contribution from current at farther distance is smaller.

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