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Is the direction of B-field due to currents west? But the compass needle points to the opposite direction? How to explain that properly?
Does the needle point to east?
Why the equation B=μ0 nI is not applicable to all solenoids?
B-field
2013-06-04 12:40 am
回答 (1)
2013-06-04 3:45 am
✔ 最佳答案
The needle points along the north-south direction.Because the two currents are in opposite direction, the B-field prodcued at A by these two currents cancel out each other, leaving only the earth magnetic field.
Q: Why the equation B=μ0 nI is not applicable to all solenoids?
A: It is only applicable to an infinitely long solenoid. For a solenoid of finite length, modification of the formula needs to be made.
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原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20130603000051KK00192