I know that for DC current, P=IV. Is this formula true for AC as well? Thanks.?

Question

Also does P=(I^2)r hold for both AC and DC?

Answer 1

For a general circuit, the formula is P ={ integral } I dV.

If you have RMS V & I , the formula DOES hold true.

Answer 2

Yes

Power voltage current resistance formulae are all used for both AC and DC solutions.

Answer 3

For AC, you will need know the Power Factor to get the true power.  Otherwise it is called VA (volt-amp).  P = V * A * power factor.

See http://en.wikipedia.org/wiki/Power_facto...

The power factor of an AC electric power system is defined as the ratio of the real power to the apparent power, and is a number between 0 and 1 (frequently expressed as a percentage, e.g. 0.5 pf = 50% pf). Real power is the capacity of the circuit for performing work in a particular time. Apparent power is the product of the current and voltage of the circuit. Due to energy stored in the load and returned to the source, or due to a non-linear load that distorts the wave shape of the current drawn from the source, the apparent power can be greater than the real power. Low-power-factor loads increase losses in a power distribution system and result in increased energy costs.