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3 Dec 2011 19:05:40 IST

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what is Irms

Physics

what is Irms

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edison

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5 Dec 2011 14:25:12 IST

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RMS and Effective Values

Circuit currents and voltages in AC circuits are generally stated as root-mean-square or rms values rather than by quoting the maximum values. The root-mean-square for a current is defined by

That is, you take the square of the current and average it, then take the square root. When this process is carried out for a sinusoidal current

Since the AC voltage is also sinusoidal, the form of the rms voltage is the same. These rms values are just the effective value needed in the expression for average power to put the AC power in the same form as the expression for DC powr in a resistor. In a resistor where the power factor is equal to 1:

Since the voltage and current are both sinusoidal, the power expression can be expressed in terms of the squares of sine or cosine functions, and the average of a sine or cosine squared over a whole period is = 1/2.

prashant jain

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9 Dec 2011 10:59:25 IST

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as u knw thar we cant calculate flow of charge over one complete cycle becoz d direction of current get reversed after every half rotaion in a.c.

thus in order to calculate current over one cycle we choose heat becoz it is independent of direction.

I.R.M.S-it is defined as dat value of steady current which would generate the same amount of heat in a given resistance in a given tym,as is done by the a.c when passed through the same resistance for the same time.

for more information-prashant2895@gmail.com

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