The electric current in a conductor varies with time according to i = (20 + 4t). Determine the value of x if the total charge passing through a section of the conductor in 10 seconds is x × 10² C.

Correct answer: 4

Solution

Charge Q = integral over 0..10 of (20+4t) dt = 20*10 + 2*10^2 = 200 + 200 = 400 C = 4 x 10^2 C. Thus x = 4, which is option index 1, not the stored index 2.

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