$(a) \;magnitude = 9 \times 10^{-3}V; \; P = +ve \; and \; Q =-ve$
$(b) \;magnitude = 9 \times 10^{-3}V; \; P = -ve \; and \; Q =+ve$
$(c) \;magnitude = 0.9 \times 10^{-3}V; \; P = +ve \; and \; Q =-ve$
$(d) \;magnitude = 0.9 \times 10^{-3}V; \; P = -ve \; and \; Q =+ve$