You are given several identical resistances each of value R = 10 Ω and each capable of carrying maximum current of 1 ampere. It is required to make a suitable combination of these resistances to produce a resistance of 5 Ω which can carry a current of 4 amperes. The minimum number of resistances of the type R that will be required for this job
(1) 4
(2) 10
(3) 8
(4) 20
In the circuit shown below, E1 = 4.0 V, R1= 2 Ω, E2 = 6.0 V, R2 = 4 Ω and R3 = 2 Ω. The current I1 is:
1. 1.6 A
2. 1.8 A
3. 1.25 A
4. 1.0 A
The potential difference across 8 ohms resistance is 48 volts as shown in the figure below. The value of potential difference across X and Y points will be:
1. 160 volt
2. 128 volt
3. 80 volt
4. 62 volt
What is the equivalent resistance between terminals A and B of the network?
1.
2. 8 Ω
3. 6 Ω
4.
A wire of resistor R is bent into a circular ring of radius r. Equivalent resistance between two points X and Y on its circumference, when angle XOY is α, can be given by
(1)
(2)
(3) R (2π – α)
(4)
As the switch S is closed in the circuit shown in the figure, the current passed through it is :
(1) 4.5 A
(2) 6.0 A
(3) 3.0 A
(4) Zero
In the following circuit, a 10 m long potentiometer wire with resistance 1.2 ohm/m, a resistance R1 and an accumulator of emf 2 V are connected in series. When the emf of the thermocouple is 2.4 mV then the deflection in the galvanometer is zero. The current supplied by the accumulator will be :
(1) 4 × 10–4 A
(2) 8 × 10–4 A
(3) 4 × 10–3 A
(4) 8 × 10–3 A
In order to quadruple the resistance of a uniform wire, a part of its length was uniformly stretched till the final length of the entire wire was 1.5 times the original length, the part of the wire was fraction equal to
(1) 1 / 8
(2) 1 / 6
(3) 1 / 10
(4) 1 / 4
Current through wire XY of circuit shown is :
(1) 1 A
(2) 4 A
(3) 2 A
(4) 3 A
12 cells each having the same emf are connected in series with some cells wrongly connected. The arrangement is connected in series with an ammeter and two similar cells which are in series. Current is 3 A when cells and battery aid each other and is 2 A when cells and battery oppose each other. The number of cells wrongly connected is/are:
1. 4
2. 1
3. 3
4. 2
If voltage across a bulb rated 220 V-100 W drops by 2.5% of its rated value, the percentage of the rated value by which the power would decrease is
(1)20%
(2)2.5%
(3)5%
(4)10%
In the circuit in the figure, if the potential at point A is taken to be zero, the potential at point B is :
1. -1V 2. +2V
3. -2V 4. +1V
A wire of a certain material is streched slowly by ten per cent. Its new resistance and specific resistance become respectively
(1) 1.2 times, 1.1 times
(2) 1.21 times,same
(3) both remain the same
(4) 1.1 times, 1.1 times
An electric kettle takes 4 A current at 220 V. How much time will it take to boil 1 kg of water from temperature C? The temperature of boiling water is C
(a) 6.3 min
(b) 8.4 min
(c) 12.6 min
(d) 4.2 min
A cell can be balanced against 110cm and 100 cm of potentiometer wire, respectively with and without being short-circuited through a resistance of . Its internal resistance is
(1) 1.0
(2) 0.5
(3) 2.0
(4) zero