Current Electricity · Question 10

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

The given circuit shows a uniform straight wire AB of 40 cm length fixed at both ends. In order to get zero reading in the galvanometer G, the free end of J is to be placed from B at: [figure]

1. 32 cm
2. 8 cm
3. 16 cm
4. 24 cm

The steady state current in the circuit shown below is : [figure]

1. 0.67 A
2. 1.5 A
3. 2 A
4. 1 A

The magnitude and direction of the current in the following circuit is :- [figure]

1. 0.5 A from A to B through E
2. 59 A from A to B through E
3. 1.5 A from B to A through E
4. 0.2 A from B to A through E

If the galvanometer G does not show any deflection in the circuit shown, the value of R is given by: [figure]

1. 50
2. 100
3. 400
4. 200

Resistance of a carbon resistor determined from colour codes is (22000 5\%) . The colour of third band must be :

1. Green
2. Orange
3. Yellow
4. Red

The resistance of platinum wire at 0 is 2 and 6.8 at 80 . The temperature coefficient of resistance of the wire is :

1. 3 10-3 -1
2. 3 10-2 -1
3. 3 10-10 -1
4. 3 10-4 -1