A) decreasea as \[\frac{1}{r}\]
B) decreases as \[\frac{1}{{{r}^{2}}}\]
C) decreases as \[\frac{1}{{{r}^{3}}}\]
D) approaches a finite limit as \[r\to \infty \]
Correct Answer: B
Solution :
(b) decreases as \[\frac{1}{{{r}^{2}}}\]. From Biot-savart's law. \[dB=\frac{{{\mu }_{0}}}{4\pi }\frac{Idl}{{{r}^{2}}}i.e.\,dB\propto \frac{1}{{{r}^{2}}}\]You need to login to perform this action.
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