The alternating current in a circuit is described by the graph shown in figure. Show rms current in this graph.
From graph diagram maximum current $\mathrm{I}_{1}=1 \mathrm{~A}$ and $\mathrm{I}_{2}=-2 \mathrm{~A}$ $\therefore$ Average maximum current $\mathrm{I}_{\mathrm{m}}=\sqrt{(1)^{2}+(-2)^{2}}$
$\therefore \mathrm{I}_{\mathrm{m}}=\sqrt{5} \mathrm{~A}$
Now, $\mathrm{I}_{\mathrm{rms}}=\frac{\mathrm{I}_{\mathrm{m}}}{\sqrt{2}}$
$=\frac{\sqrt{5}}{\sqrt{2}}=\sqrt{\frac{5}{2}}=\sqrt{2.5}=1.58 \mathrm{~A}$
$\therefore \mathrm{I}_{\mathrm{rms}} \approx 1.6 \mathrm{~A}$ is shown in below graph.
The instantaneous voltages at three terminals marked $\mathrm{X}, \mathrm{Y}$ and $\mathrm{Z}$ are given by
$V_x=V_0 \sin \omega t$ $V_y=V_0 \sin \left(\omega t+\frac{2 \pi}{3}\right) \text { and }$ $V_z=V_0 \sin \left(\omega t+\frac{4 \pi}{3}\right)$
An ideal voltmeter is configured to read rms value of the potential difference between its terminals. It is connected between points $\mathrm{X}$ and $\mathrm{Y}$ and then between $\mathrm{Y}$ and $\mathrm{Z}$. The reading(s) of the voltmeter will be
$[A]$ $\mathrm{V}_{\mathrm{XY}}^{\mathrm{mms}}=\mathrm{V}_0 \sqrt{\frac{3}{2}}$
$[B]$ $\mathrm{V}_{\mathrm{YZ}}^{\mathrm{mms}}=\mathrm{V}_0 \sqrt{\frac{1}{2}}$
$[C]$ $\mathrm{V}_{\mathrm{XY}}^{\mathrm{mms}}=\mathrm{V}_0$
$[D]$ independent of the choice of the two terminals
In $ac$ circuit when $ac$ ammeter is connected it reads $i$ current if a student uses $dc$ ammeter in place of $ac$ ammeter the reading in the $dc$ ammeter will be:
Statement $-1$ : Capacitor can be used in $a.c.$ circuit in place of choke coil.
Statement $-2$ : Capacitor blocks $d.c.$ and allows $a.c.$ only.
If instantaneous current is given by $i = 4\cos \,(\omega \,t + \phi )$ amperes, then the $r.m.s$. value of current is
In a circuit, current varies with time as $i = 2\sqrt t $ . Root mean square value of current for interval $t = 2\,s$ to $t = 4\,s$ is