Resistances in the circuit of fig. are of R $$\Omega$$ each. The switch is initially open. What happens to the lamp's intensity when the switch is closed?

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

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

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