
$\mathrm{V}_{\mathrm{P}}-\mathrm{V}_{\mathrm{S}}=7.5 \times 3=22.5$ $\mathrm{volt}$
but $\mathrm{V}_{\mathrm{S}}=0 \quad$ so $\mathrm{V}_{\mathrm{P}}=22.5$ $\mathrm{volt}$
$\mathrm{V}_{\mathrm{R}}-\mathrm{V}_{\mathrm{Q}}=1 \times 3$
$\mathrm{V}_{\mathrm{Q}}=-3 \mathrm{\,V}$




($A$) The voltmeter displays $-5 \mathrm{~V}$ as soon as the key is pressed, znd displays $+5 \mathrm{~V}$ after a long time
($B$) The voltmeter will display $0 \mathrm{~V}$ at time $t=\ln 2$ seconds
($C$) The current in the ammeter becomes $1 / e$ of the initial value after $1$ second
($D$) The current in the ammeter becomes zero after a long time