A) 8 A
B) 10 A
C) 12 A
D) 14 A
Correct Answer: A
Solution :
The coercivity of bar magnet is \[4\times {{10}^{3}}\,A{{m}^{-1}}\] i.e., it requires a magnetic intensity \[H=4\times {{10}^{3}}A{{m}^{-1}}\]to get demagnetized. Let \[i\]be the current carried by solenoid having n number of turns per metre length, then \[H=ni\] Here \[H=4\times {{10}^{3}}A{{m}^{-1}}\] and \[n=\frac{N}{l}=\frac{60}{0.12}=500\,\text{turn/m}\] \[\therefore \] \[i=\frac{H}{n}=\frac{4\times {{10}^{3}}}{500}=8.0\,A\]You need to login to perform this action.
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