Question $9(5$ points$)$

$A120F$ capacitor is connected to a $15\mathrm{.}0$ V power supply. Once the capacitor is fully charged the power supply is disconnected so that the charge on the capacitor remains constant. A piece of material having a dielectric constant of $3\mathrm{.}75$ is placed between the plates, completely filling the space between them. By how much did the energy stored in the capacitor change during the insertion?

$-9\mathrm{.}90$ mJ

$-5\mathrm{.}28$ mJ

$-3\mathrm{.}63$ mJ

$-2\mathrm{.}64$ mJ

$-1\mathrm{.}90$ mJ

$-0\mathrm{.}964$ mJ

$0$ mJ

$+0\mathrm{.}964$ mJ

$+1\mathrm{.}90$ mJ

$+2\mathrm{.}64$ mJ

$3\mathrm{.}63$ mJ

$+5\mathrm{.}28$ mJ

$+9\mathrm{.}90mJ$