Both alternating current and direct current are measured in amperes. But how is the ampere defined for an alternating current?
(N/A) For a direct current $(DC)$,$1$ ampere is defined as $1$ coulomb of charge flowing per second.
An alternating current $(AC)$ changes its direction periodically with the source frequency. If we were to measure the average current,it would be zero over a full cycle,which is not useful for power measurement.
Therefore,the $AC$ ampere is defined based on a property that is independent of the direction of current,which is the heating effect (Joule's heating).
$1$ ampere of $AC$ is defined as the value of alternating current that produces the same amount of heat in a given resistor as $1$ ampere of $DC$ would produce in the same resistor over the same time interval. This is known as the root-mean-square $(RMS)$ value of the current.
An alternating current $(AC)$ changes its direction periodically with the source frequency. If we were to measure the average current,it would be zero over a full cycle,which is not useful for power measurement.
Therefore,the $AC$ ampere is defined based on a property that is independent of the direction of current,which is the heating effect (Joule's heating).
$1$ ampere of $AC$ is defined as the value of alternating current that produces the same amount of heat in a given resistor as $1$ ampere of $DC$ would produce in the same resistor over the same time interval. This is known as the root-mean-square $(RMS)$ value of the current.
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Similar Questions
An alternating current is given by $I=100 \sin (50 \pi t)$. How many times will the current become zero in one second (in $times$)?
$A$ bulb of resistance $280 \Omega$ is supplied with a $200 V$ $AC$ supply. What is the peak current?
The ratio of the peak value to the root mean square (r.m.s.) value of an alternating current is:
Easy
View SolutionFor an $AC$ current $I = 50 \cos(100t + 45^{\circ}) \ A$. The value of $I_{rms} =$ . . . . . . $A$.
The instantaneous voltages at three terminals marked $X, Y$ and $Z$ are given by
$V_x = V_0 \sin \omega t$
$V_y = V_0 \sin \left(\omega t + \frac{2 \pi}{3}\right)$
$V_z = V_0 \sin \left(\omega t + \frac{4 \pi}{3}\right)$
An ideal voltmeter is configured to read the $rms$ value of the potential difference between its terminals. It is connected between points $X$ and $Y$ and then between $Y$ and $Z$. The reading$(s)$ of the voltmeter will be:
$[A]$ $V_{XY}^{rms} = V_0 \sqrt{\frac{3}{2}}$
$[B]$ $V_{YZ}^{rms} = V_0 \sqrt{\frac{1}{2}}$
$[C]$ $V_{XY}^{rms} = V_0$
$[D]$ independent of the choice of the two terminals
$V_x = V_0 \sin \omega t$
$V_y = V_0 \sin \left(\omega t + \frac{2 \pi}{3}\right)$
$V_z = V_0 \sin \left(\omega t + \frac{4 \pi}{3}\right)$
An ideal voltmeter is configured to read the $rms$ value of the potential difference between its terminals. It is connected between points $X$ and $Y$ and then between $Y$ and $Z$. The reading$(s)$ of the voltmeter will be:
$[A]$ $V_{XY}^{rms} = V_0 \sqrt{\frac{3}{2}}$
$[B]$ $V_{YZ}^{rms} = V_0 \sqrt{\frac{1}{2}}$
$[C]$ $V_{XY}^{rms} = V_0$
$[D]$ independent of the choice of the two terminals
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