A piece of copper and another of germanium are cooled from room temperature to 80K.The resistance of
each of them increases
each of them decreases
copper increases and germanium decreases
copper decreases and germanium increases
A storage battery is connected to the mains for charging with emf of 12.5 V. The internal resistance of the storage battery is 1 Ω. When the charging current is 0.5 A, the potential difference across the storage battery is
13 V
12.5 V
12 V
11.5 V
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
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
Kirchhoff's current law at a junction deals with conservation of
charge
energy
momentum
all of these
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
A condenser having a capacity of 2 μF is charged to 200 V and then the plates of the capacitor are connected to a resistance wire.The heat produced is
2 x 10-2 J
4 x 10-2 J
4 x 10-4 J
4 x 1010 J
