In a potentiometer of 10 wires,the balance point is obtained on the 7th wire.To shift the balance point to 9th wire,we should
decrease resistance in the main circuit
increase resistance in the main circuit
decrease resistance in series with the cell whose emf is to be measured
increase resistance in series with the cell whose emf is to be determined
The length of a potentiometer wire is 5 metres. An electron in this wire experiences a force of 4.8 × 10-19 newton, emf of the main cell used in potentiometer is
infinite
zero
minimum
maximum
A 10 metre potentionmeter wire has a resistance of 20 Ω. It is connected in series with a battery of emf 2.5 volt and a resistance of 5 Ω. The potential gradient along wire in volt cm-1 is
0.002
0.02
0.2
0.0025
The negative Zn pole of a Daniell cell, sending a contant current through a circuit, decreases in mass by 0.13 g in 30 minutes. If the electrochemical equivalent of Zn and Cu are 32.5 and 31.5 respectively, the increase in the mass of the positive Cu pole in this time is
0.180 g
0.141 g
0.126 g
0.242 g
Iron and silicon wires are heated from 30°C to 50°C.The correct statement is that
resistance of both the wires increases
resistance of both the wires decreases
resistance of iron wire increases and that of silicon wire decreases
resistance of iron wire decreases and that of silicon wire increases
Four bulbs marked 40 W, 250 V are connected in series with 250 V mains, the total power consumed is
10 W
40 W
320 W
160 W
A 2 kW boiler used for 1 hour everyday consumes electrical energy in thirty days equal to
120 units
60 units
15 units
30 units
Potentiometer measures the potential difference more accurately than a voltmeter because
it has a wire of high resistance
it has a wire of low resistance
it does not draw current from external circuit
it draws a heavy current from external circuit
A 220 volt, 1000 watt bulb is connected across a 110 volt mains supply. The power consumed will be
750 watt
500 watt
250 watt
1000 watt
Kirchhoff's current law at a junction deals with conservation of
charge
energy
momentum
all of these
