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In the circuit shown in the figure, the switch was kept in p o s i t i o n - 1 for a very long time and then at t = 0 it is shifted to p o s i t i o n - 2 . The current in the circuit immediately after that is i = a b   A , then the value of a + b is

Correct answer

7

Step-by-step solution

The total flux, before and after the position change of the switch, remains the same L 1 i 1 = L 2 i 2 L 1 = 5 H , i 1 = 4 A and L 2 = 15 H 5 × 4 = 15 × i ⇒ i = 4 3 = a b ⇒ a + b = 7

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