Current Electricity · Question 4

Consider two circuits, (A) and (B), each having two resistors. One of them has a positive temperature coefficient of resistance, + , while the other one has a negative temperature of coefficient, - , as shown in the figure. The current through these circuits are denoted by IA and IB. At initial temperature, the resistance of the two resistors is R0. As the temperature is increased, the correct option that describes the variation of current in these circuits is: [figure]

1. both IA and IB remain constant
2. IA remains constant while IB increases
3. IA decreases while IB increases
4. IA increases while IB decreases

The current passing through the battery in the given circuit, is: [figure]

1. 2.5 A
2. 1.5 A
3. 2.0 A
4. 0.5 A

A wire of resistance R is cut into 8 equal pieces. From these pieces two equivalent resistances are made by adding four of these together in parallel. Then these two sets are added in series. The net effective resistance of the combination is:

1. R16
2. R8
3. R64
4. R32

A constant voltage of 50 V is maintained between the points A and B of the circuit shown in the figure. The current through the branch CD of the circuit is: [figure]

1. 2.5 A
2. 3.0 A
3. 1.5 A
4. 2.0 A

The terminal voltage of the battery, whose emf is 10 V and internal resistance 1 , when connected through an external resistance of 4 as shown in the figure is: [figure]

1. 4 V
2. 6 V
3. 8 V
4. 10 V

A wire of length 'l' and resistance 100 is divided into 10 equal parts. The first 5 parts are connected in series while the next 5 parts are connected in parallel. The two combinations are again connected in series. The resistance of this final combination is:

1. 26
2. 52
3. 55
4. 60

Two heaters A and B have power rating of 1 kW and 2 kW, respectively. Those two are first connected in series and then in parallel to a fixed power source. The ratio of power outputs for these two cases is:

1. 1:1
2. 2:9
3. 1:2
4. 2:3

Choose the correct circuit which can achieve the bridge balance.

1. [figure]
2. [figure]
3. [figure]
4. [figure]

A uniform wire of diameter d carries a current of 100 mA when the mean drift velocity of electrons in the wire is v. For a wire of diameter d2 of the same material to carry a current of 200 mA, the mean drift velocity of electrons in the wire is

1. 4v
2. 8v
3. v
4. 2v

A uniform metal wire of length l has 10 resistance. Now this wire is stretched to a length 2l and then bent to form a perfect circle. The equivalent resistance across any arbitrary diameter of that circle is

1. 10
2. 5
3. 40
4. 20