A storage battery of emf $$28.0 \mathrm{~V}$$ and internal resistance $$0.5 \Omega$$ is being charged by a $$140 \mathrm{~V}$$ dc supply using a series resistor of $$27.5 \Omega$$. The terminal voltage of the battery during charging is

The resistance of the galvanometer and shunt of an ammeter are $$90 \mathrm{~ohm}$$ and $$10 \mathrm{~ohm}$$ respectively, then the fraction of the main current passing through the galvanometer and the shut respectively are:

A $$500 \mathrm{~W}$$ heating unit is designed to operate on a $$400 \mathrm{~V}$$ line. If line voltage drops to $$160 \mathrm{~V}$$, the percentage drop in heat output will be:

A cell of emf E and internal resistance r is connected to two external resistances $$\mathrm{R_1}$$ and $$\mathrm{R_2}$$ and a perfect ammeter. The current in the circuit is measured in four different situations:

(a) without any external resistance in the circuit.

(b) with resistance $$\mathrm{R_1}$$ only

(c) with $$\mathrm{R_1}$$ and $$\mathrm{R_2}$$ in series combination.

(d) with $$\mathrm{R_1}$$ and $$\mathrm{R_2}$$ in parallel combination.

The currents measured in the four cases in ascending order are