Current Electricity

In the circuit shown, if a conducting wire is connected between points A and B, the current in this wire will [figure]

1. flow from B to A
2. flow from A to B
3. flow in the direction which will be decided by the value of V
4. be zero

Kirchhoff's first and second laws of electrical circuits are consequences of

1. conservation of energy and electric charge respectively
2. conservation of energy
3. conservation of electric charge and energy respectively
4. conservation of electric charge

Two cells, having the same e.m.f. are connected in series through an external resistance R. Cells have internal resistances r1 and r2 (r1 > r2) respectively. When the circuit is closed, the potential difference across the first cell is zero. The value of R is

1. r1 + r2
2. r1 - r2
3. r1 + r22
4. r1 - r22

Power dissipated across the 8 Ω resistor in the circuit shown here is 2 watt. The power dissipated in watt units across the 3 Ω resistor is [figure]

1. 3.0
2. 2.0
3. 1.0
4. 0.5

Two batteries, one of emf 18 volts and internal resistance 2 and the other of emf 12 volts and internal resistance 1 , are connected as shown. The voltmeter V will record a reading of [figure]

1. 30 volt
2. 18 volt
3. 15 volt
4. 14 volt

When a wire of uniform cross-section a, length l and resistance R is bent into a complete circle, the resistance between any two diametrically opposite points will be

1. R/4
2. 4R
3. R/8
4. R/2

For the network shown in the figure the value of the current i is [figure]

1. 9V35
2. 18V5
3. 5V9
4. 5V18

A 5-ampere fuse wire can withstand a maximum power of 1 watt in the circuit. The resistance of the fuse wire is

1. 0.04 ohm
2. 0.2 ohm
3. 5 ohm
4. 0.4 ohm

The electric resistance of a certain wire of iron is R. If its length and radius are both doubled, then

1. The resistance will be doubled and the specific resistance will be halved.
2. The resistance will be halved and the specific resistance will remain unchanged.
3. The resistance will be halved and the specific resistance will be doubled.
4. The resistance and the specific resistance, will both remain unchanged.

Resistances n, each of r ohm, when connected in parallel give an equivalent resistance of R ohm. If these resistances were connected in series, the combination would have a resistance in ohms, equal to

1. n2R
2. R/n2
3. R/n
4. nR