A resistance of 4 Ω and a wire of length 5 metres and resistance 5 Ω are joined in series and connected to a cell of e.m.f. 10 V and internal resistance 1 Ω. A parallel combination of two identical cells is balanced across 300 cm of the wire. The e.m.f. E of each cell is
1.5 V
3.0 V
0.67 V
1.33 V
Constantan wire is used in making standard resistances because of its :
Specific resistance is low
Density is high
Temperature coefficient of resistance is negligible
Melting point is high
A potentiometer consists of a wire of length 4 m and resistance 10 Ω. It is connected to a cell of e.m.f. 2 V. The potential difference per unit length of the wire will be :
0.5 V/m
2 V/m
5 V/m
10 V/m
In the circuit shown P≠R, the reading of the galvanometer is same with switch S open or closed. Then
IR=IG
IP=IG
IQ=IG
IQ=IR
In the following Wheatstone bridge P/Q=R/S. If key K is closed, then the galvanometer will show deflection :
In left side
In right side
No deflection
In either side
In a potentiometer experiment, the galvanometer shows no deflection when a cell is connected across 60 cm of the potentiometer wire. If the cell is shunted by a resistance of 6 Ω, the balance is obtained across 50 cm of the wire. The internal resistance of the cell is
0.5 Ω
0.6 Ω
1.2 Ω
1.5 Ω
In the adjoining circuit, the e.m.f. of the cell is 2 volt and the internal resistance is negligible. The resistance of the voltmeter is 80 ohm. The reading of the voltmeter will be
1.60 volt
1.33 volt
2.00 volt
A voltmeter has resistance of 2000 ohms and it can measure upto 2V. If we want to increase its range to 10 V, then the required resistance in series will be
2000 Ω
4000 Ω
6000 Ω
8000 Ω
In the given figure, battery E is balanced on 55 cm length of potentiometer wire but when a resistance of 10 Ω is connected in parallel with the battery then it balances on 50 cm length of the potentiometer wire then internal resistance r of the battery is
1 Ω
3 Ω
10 Ω
5 Ω
In the circuit shown, a meter bridge is in its balanced state. The meter bridge wire has a resistance 0.1 ohm/cm. The value of unknown resistance X and the current drawn from the battery of negligible resistance is
6 Ω, 5 amp
10 Ω, 0.1 amp
4 Ω, 1.0 amp
12 Ω, 0.5 amp
AB is a potentiometer wire of length 100 cm and its resistance is 10 ohms. It is connected in series with a resistance R = 40 ohms and a battery of e.m.f. 2 V and negligible internal resistance. If a source of unknown e.m.f. E is balanced by 40 cm length of the potentiometer wire, the value of E is
0.8 V
1.6 V
0.08 V
0.16 V
The measurement of the voltmeter in the following circuit is :
2.4 V
3.4 V
4.0 V
6.0 V
The potential difference across the 100Ω resistance in the following circuit is measured by a voltmeter of 900 Ω resistance. The percentage error made in reading the potential difference is :
109
0.1
1.0
10.0
If the ammeter in the given circuit reads 2 A, the resistance R is :
1 ohm
2 ohm
3 ohm
4 ohm
Two resistances of 400 Ω and 800 Ω are connected in series with a 6-volt battery of negligible internal resistance. A voltmeter of resistance 10,000 Ω is used to measure the potential difference across 400 Ω. The error in the measurement of potential difference in volts approximately is :
0.01
0.02
0.03
0.05
The length of a wire of a potentiometer is 100 cm, and the emf of its standard cell is E volt. It is employed to measure the e.m.f of a battery whose internal resistance is 0.5 Ω. If the balance point is obtained at l = 30 cm from the positive end, the e.m.f. of the battery is :
30E100
30E100.5
30E(100−0.5)
30(E−0.5i)100, where i is the current in the potentiometer
What is the reading of the voltmeter in the following figure?
3 V
2 V
5 V
4 V
In a metre bridge experiment, the null point is obtained at 20 cm from one end of the wire when resistance X is balanced against another resistance Y. If X < Y, then where will be the new position of the null point from the same end, if one decides to balance a resistance of 4X against Y
50 cm
80 cm
40 cm
70 cm
In given figure, the potentiometer wire AB has a resistance of 5 Ω and length 10 m. The balancing length AM for the emf of 0.4 V is :
0.4 m
4 m
0.8 m
8 m
If the resistance of voltmeter is 10000Ω and resistance of ammeter is 2Ω then find R when voltmeter reads 12V and ammeter reads 0.1 A :
118 Ω
120 Ω
124 Ω
114Ω
Potentiometer wire of length 1 m is connected in series with 490 Ω resistance and 2V battery. If 0.2 mV/cm is the potential gradient, then the resistance of the potentiometer wire is :
4.9 Ω
7.9 Ω
5.9 Ω
6.9 Ω
In an electrical cable, there is a single wire of radius 9 mm of copper. Its resistance is 5 Ω. The cable is replaced by 6 different insulated copper wires, the radius of each wire is 3 mm. Now the total resistance of the cable will be :
7.5 Ω
45 Ω
90 Ω
270 Ω
Two uniform wires A and B are of the same metal and have equal masses. The radius of wire A is twice that of wire B. The total resistance of A and B when connected in parallel is :
4 Ω when the resistance of wire A is 4.25 Ω
5 Ω when the resistance of wire A is 4.25 Ω
4 Ω when the resistance of wire B is 4.25 Ω
7 Ω when the resistance of wire B is 4.25 Ω
Twelve wires of equal length and same cross-section are connected in the form of a cube. If the resistance of each of the wires is R, then the effective resistance between the two diagonal ends would be
2R
12R
56R
8R
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
4
10
8
20
The resistance of a wire is 10–6 Ω per metre. It is bend in the form of a circle of diameter 2 m. A wire of the same material is connected across its diameter. The total resistance across its diameter AB will be
43π×10−6Ω
23π×10−6Ω
0.88×10−6Ω
14π×10−6Ω
In the figure shown, the capacity of the condenser C is 2 μF. The current in 2 Ω resistor is :
19A
9 A
0.9 A
10.9A
When the key K is pressed at time t = 0, which of the following statements about the current I in the resistor AB of the given circuit is true?
I = 2 mA at all t
I oscillate between 1 mA and 2mA
I = 1 mA at all t
At t = 0 , I = 2 mA and with time it goes to 1 mA
There are three resistance coils of equal resistance. The maximum number of resistances you can obtain by connecting them in any manner you choose, being free to use any number of the coils in any way is :
3
6
5
If in the circuit shown below, the internal resistance of the battery is 1.5 Ω and VP and VQ are the potentials at P and Q respectively, what is the potential difference between the points P and Q
Zero
4 volts (VP > VQ)
4 volts (VQ > VP)
2.5 volts (VQ > VP)
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