Input resistance for AC input

It's not a definition that I've seen. It doesn't strike me as a good definition in general because the math would get a little dicey at the zero crossings. Otherwise I guess it would be basically correct for a resistive network, even if resistances changed with time.

Yes. Its wrong. Input resistance of an ideal voltage source is Zero. pls click the following link for more iformation

-------------------- The input resistance implied is not that of the source but that of the circuit supplied by the load-as seen by the source and is independent of the source.
In any case, an ideal voltage source is a convenient fiction useful in circuit analysis but hard to find in the real world (sure with fast enough feedback one can come close).
As for the definition- it simply notes that v(t)=R*i(t) rather than v(t)=L*(di/dt) or i(t)=C*(dv(t)/dt That is correct.
If R is constant over the range of possible v(t), i(t) then be happy, Ohm's Law is valid and life is simple(?) .--
Don Kelly snipped-for-privacy@shawcross.ca remove the X to answer ----------------------------