Checkpoint $26\mathrm{.}5\mathrm{.}1$A potential difference. V is connected across a device with resistance R$,$ causing current i through the device. Rank the following variations according to the change in the rate at which electrical energy is converted to thermal energy due to the resis$-$tance$,$ greatest change first: $($a$)$ V is doubled with R unchanged, $($b$)/$ is doubled with R unchanged, $($c$)$ R is doubled with V unchanged, $($d$)$ R is doubled with $/$ unchanged.