A source of e.m.f. E=15 V and having negligible internal resistan… - Vidyadip

MCQ

A source of e.m.f. $E=15 V$ and having negligible internal resistance is connected to a variable resistance so that the current in the circuit increases with time as $i=1.2 t+3$. Then, the total charge that will flow in first five second will be

A
$10 \mathrm{C}$
B
$20 \mathrm{C}$
✓
$30 \mathrm{C}$
D
$40 C$

✓

Answer

Correct option: C.

$30 \mathrm{C}$

$ i=\frac{d Q}{d t} \Rightarrow d Q=i d t \Rightarrow Q=\int_{t_1}^{t_2} i d t=\int_0^5(1.2 t+3) d t $
$ =\left[\frac{1.2 t^2}{2}+3 t\right]_0^5=30 \ C$

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