Physics-
General
Easy
Question
and 
are long parallel conductors separated by certain distance. 
is the mid-point between them (see the figure). The net magnetic field at is 
. Now, the current 2 A is switched off. The field at now becomes
The correct answer is:
Magnetic field at mid-point in first case is 
When the current 2 A is switched off, the net magnetic field at is due to current 1 A
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