All the resistances in the circuit of Fig. are of 1 $$\Omega$$ each. The value of current 'I' is

A resistance is measured by the voltmeter- ammeter method employing d.c. excitation and a voltmeter of very high resistance connected directly across the unknown resistance. If the voltmeter and ammeter readings are subject to maximum possible errors of $$ \pm 2.4\% $$ and $$ \pm 1.0\% $$ respectively, then the magnitude of the maximum possible percentage error in the value of resistance deduced from the measurement is nearly

An unshielded moving iron voltmeter is used to measure the voltage in an a.c. circuit. If a stray d.c. magnetic field having a component along the axis of the meter coil appears, the meter reading would be

In $$d.c.$$ potentiometer measurements, a second reading is often taken after reversing the polarities of the $$s.c.$$ supply and the unknown voltage, and the average of the two readings is taken. This is, with a view to eliminate the effects of