Amechanical device requires 420 j of work to do 230 j of work to lift a crate. what is the efficiency of the device? 190% 0.5% 183% 55%

Imagine that the rightward current flows in the rod for a short time. as a result, what will the net charge on the right and left ends of the rod become? left end negative and right end positive left end negative and right end negative left end negative and right end nearly neutral left end nearly neutral and right end positive both ends nearly neutral