The current in a wire varies with time according to the relation `i=(3.0A)+(2.0A//s)t`
a. How many coulomns of charge pass a cross section of the wire in the time internal between `t=0` and `t=4.0s`?
b. What constant current would transport the same charge in the same time interval?

Explanation

a. `i=(dq)/(dt)`
`:. int_0^q dq= int_0^4 idt`
`:. q=int_0^4(3+2t)dt`
`=[3t+t^2]_0^4=[12+16]`
`=28C`
`b. i=1/t=28/4=7A`