A part of a circuit is shown in the figure. The ratio of the potential differences between the points $A$ and $C$ and the points $D$ and $E$ is

A wire of resistance ' $R$ ' is bent in the form of a circular loop. Two points on the circle seperated by a quarter circumference are connected to a battery of emf ' $E$ ' and negligible internal resistance. The heat generated in the wire per second is

When a wire is connected in the left gap of a metre bridge, the balancing point is at 40 cm from the left end of the bridge wire. If the wire in the left gap is stretched so that its length is doubled and again connected in the same gap, then the balancing point from the left end of the bridge wire is