Question: AC Voltage and Current variables
Maxwell-Faraday's Law of induction says:

$$\varepsilon= -\frac{d\Phi_B}{dt}$$

Find out more on Wikipedia. The electromotive force \$\varepsilon\$ over a loop is given by the rate-of-change of the magnetic flux through that loop.

The amount of current depends on the situation and what is dissipating the generated power. A moving current through a loop will generate an opposite magnetic flux (Ampere's Law) to the one applied, which needs to be accounted for in Maxwell-Faraday's Law, and vice-versa. It basically uses the same principles as the self-inductance of an inductor.