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
An electirc kettle boils 1 kg of water in time t1 and another kettle boils the same amount of water in time t2. When they are joined in series, the time required to boil 1 kg of water is
t1 + t2
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 series with 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 determine
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
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
increase resistance in the main circuit
increase resistance in series with the cell whose emf is to be determined
The resistance of hot tungsten filament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 V lamp when not in use?
20 Ω
40 Ω
200Ω
400Ω
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
The resistance of a discharge tube is
ohmic
non - ohmic
infinity
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
The resistor R1 dissipates power P, when connected to a generator. If a resistor R2 is inserted in series with R1, the power dissipated by R1
increases
decrease
remains the same
may increase or decrease depending on the value fo R1 and R2
