P$4\mathrm{.}19$ A synchronous condenser has a synchronous reactance of $0\mathrm{.}75$ pu$.$ Given that it operates at its nominal voltage, how much reactive power does it provide if:

$($a$)$ The magnitude of the internal emf is adjusted at $1\mathrm{.}3$ pu$?$

$($b$)$ The magnitude of the internal emf is adjusted at $0\mathrm{.}8$ pu$?$