Current Electricity

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

Five equal resistances each of resistance R are connected as shown in the figure. A battery of V volts is connected between A and B. The current flowing in AFCEB will be [figure]

1. 3VR
2. VR
3. V2R
4. 2VR

A 6 volt battery is connected to the terminals of a three metre long wire of uniform thickness and resistance of 100 ohm. The difference of potential between two points on the wire separated by a distance of 50 cm will be

1. 2 volt
2. 3 volt
3. 1 volt
4. 1.5 volt

When three identical bulbs of 60 watt, 200 volt rating are connected in series to a 200 volt supply, the power drawn by them will be

1. 60 watt
2. 180 watt
3. 10 watt
4. 20 watt

In India electricity is supplied for domestic use at 220 V. It is supplied at 110 V in USA. If the resistance of a 60 W bulb for use in India is R, the resistance of a 60 W bulb for use in USA will be

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

In a Wheatstone's bridge all the four arms have equal resistance R. If the resistance of the galvanometer arm is also R, the equivalent resistance of the combination as seen by the battery is

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