Question Details

The current flowing through a wire as a function fo time is given as: I = 3t² + 2t + 5 The charge flowing through any cross-section of the wire in first 2 s is:

Options

A

5 C


B

17 C


C

16 C

D

22 C

Show Answer

Correct Answer :

Option D

22 C

Solution :

The correct option is 22 C.

To find the total charge flowing through any cross-section of the wire, we use the relationship between electric current and electric charge. Electric current is defined as the rate of flow of charge with respect to time:

I = d q d t

This equation can be rearranged to express the small amount of charge, dq, that flows in an infinitesimal time interval, dt:

d q = I d t

To determine the total charge q that flows through the wire in the first 2 seconds (from t=0 to t=2 s), we integrate both sides of the equation over this time range:

q = 0 2 I t

We are given the current as a function of time: I=3t2+2t+5. Substituting this expression into our integral, we get:

q = 0 2 ( 3 t 2 + 2 t + 5 ) t

We now integrate each term individually with respect to t:

q = [ 3 t 3 3 + 2 t 2 2 + 5 t ] 0 2

Simplifying the coefficients gives:

q = [ t 3 + t 2 + 5 t ] 0 2

Now, evaluate the antiderivative at the upper limit of integration (2) and subtract the value at the lower limit (0):

q = 2 3 + 2 2 + 5 ( 2 ) - 0 3 + 0 2 + 5 ( 0 )

q = ( 8 + 4 + 10 ) - 0

q = 22 C

Therefore, the charge flowing through any cross-section of the wire in the first 2 seconds is 22 C.

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