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Current Electricity

178 Questions Start Allen Test
All Exams Allen
Q76 Allen CELLS & COMBINATION OF CELLS, ELECTRIC POWER & ENERGY MCQ
A cell supplies a current of 0.9 A through a 2 Ω resistor and a current of 0.3 A through a 7 Ω resistor. The internal resistance of the cell is:
A.
1.0 Ω
B.
0.5 Ω
C.
2.0 Ω
D.
1.2 Ω
Q77 Allen CELLS & COMBINATION OF CELLS, ELECTRIC POWER & ENERGY MCQ
A 10 V battery with internal resistance 0.5 Ω is connected across a variable resistance R. The value of R for which the power delivered to it is maximum, is equal to
A.
0.5 Ω
B.
1 Ω
C.
1.5 Ω
D.
2 Ω
Q78 Allen CELLS & COMBINATION OF CELLS, ELECTRIC POWER & ENERGY MCQ
An electric bulb is designed to draw a power $P_{0}$ at voltage $V_{0}$ . If the voltage is V, it draws a power P, then -
A.
$P = \left( \frac{V}{V_{0}} \right) P_{0}$
B.
$P = \left( \frac{V_{0}}{V} \right) P_{0}$
C.
$P = \left( \frac{V_{0}}{V} \right)^{2} P_{0}$
D.
$P = \left( \frac{V}{V_{0}} \right)^{2} P_{0}$
Q79 Allen CELLS & COMBINATION OF CELLS, ELECTRIC POWER & ENERGY MCQ
Consider the four circuits shown in the figure below. In which circuit power dissipated maximum (Neglect the internal resistance of the power supply)
A.
B.
C.
D.
Q80 Allen CELLS & COMBINATION OF CELLS, ELECTRIC POWER & ENERGY MCQ
Three resistances of equal value are arranged in different combinations as shown below. Arrange them in the increasing order of power dissipation:
(I)

(II)

(III)

(IV)
A.
III < II < IV < I
B.
II < III < IV < I
C.
I < IV < III < II
D.
I < III < II < IV
Q81 Allen CELLS & COMBINATION OF CELLS, ELECTRIC POWER & ENERGY MCQ
25 W, 200 V and 100 W, 200 V bulbs are connected in series to a source of 400 volts. Which bulb will fuse?
A.
25 W
B.
100 W
C.
Both will fuse at the same time
D.
None of the bulbs will fuse
Q82 Allen CELLS & COMBINATION OF CELLS, ELECTRIC POWER & ENERGY MCQ
You are provided with 48 cells, each of emf 2 volts and internal resistance 4 ohms. What maximum current can flow in the circuit having an external resistance of $12\Omega$ ?
A.
1 A
B.
1.2 A
C.
0.96 A
D.
1.08 A
Q83 Allen CELLS & COMBINATION OF CELLS, ELECTRIC POWER & ENERGY MCQ
Two electric bulbs of the same power, but with different marked voltages are connected in series across a power line. Their brightness will be :-
A.
directly proportional to their marked voltages
B.
inversely proportional to their marked voltages
C.
directly proportional to the squares of their marked voltages
D.
inversely proportional to the squares of their marked voltages
Q84 Allen CELLS & COMBINATION OF CELLS, ELECTRIC POWER & ENERGY MCQ
Four circuits are shown below. All the batteries have the same voltage V and all resistors have the same resistance R. In which circuit does the battery delivers the most power?
A.
B.
C.
D.
Q85 Allen CELLS & COMBINATION OF CELLS, ELECTRIC POWER & ENERGY MCQ
Two cells, each of e.m.f. E and internal resistance r, are connected in parallel across a resistor R. The power dissipated in the resistor is maximum if:
A.
R = r
B.
R = 2r
C.
$R = \frac{3r}{2}$
D.
$R = \frac{r}{2}$
Q86 Allen CELLS & COMBINATION OF CELLS, ELECTRIC POWER & ENERGY MCQ
In the circuit shown in figure, the power which is dissipated as heat in the $6 \Omega$ resistor is 6 W. What is the value of resistance R in the circuit?
A.
$6\Omega$
B.
$10\Omega$
C.
$13\Omega$
D.
$24\Omega$
Q87 Allen CELLS & COMBINATION OF CELLS, ELECTRIC POWER & ENERGY MCQ
For different values of resistance, R power consumptions in R are given. Then which of the following values are not possible?

(a) 2 W (b) 5 W (c) 8 W (d) 4 W
A.
Only c
B.
b & c
C.
a, b, c
D.
All
Q88 Allen MEASURING DEVICES MCQ
An ammeter and a voltmeter are joined in series to a cell. Their readings are A and V respectively. If a resistance is now joined in parallel with the voltmeter
A.
both A and V will decrease
B.
both A and V will increase
C.
A will increase, V will decrease
D.
A will decrease, V will increase
Q89 Allen MEASURING DEVICES MCQ
A galvanometer of 100 Ω resistance yields complete deflection when 10 mA current flows. What should be the value of shunt so that it can measure currents upto 100 mA?
A.
11.11 Ω
B.
9.9 Ω
C.
1.1 Ω
D.
4.4 Ω
Q90 Allen MEASURING DEVICES MCQ
In order to change the range of a galvanometer of G Ω resistance from V volts to nV volts what will be the value of resistance in Ω connected in series with it:-
A.
(n-1)G
B.
$\frac{G}{n}$
C.
nG
D.
$\frac{G}{n-1}$
Q91 Allen MEASURING DEVICES MCQ
Resistance in the two gaps of a meter bridge are 10 ohms and 30 ohms respectively. If the resistances are interchanged, the balance point shifts by :-
A.
33.3 cm
B.
66.67 cm
C.
25 cm
D.
50 cm
Q92 Allen MEASURING DEVICES MCQ
A galvanometer acting as a voltmeter will have :
A.
a high resistance in series with its coil
B.
a low resistance in parallel with its coil
C.
a low resistance in series with its coil
D.
a high resistance in parallel with its coil
Q93 Allen MEASURING DEVICES MCQ
In the shown arrangement of the experiment of a meter bridge if AC, corresponding to null deflection of galvanometer, is x then what would be its value if the radius of the wire AB is doubled:-
A.
x
B.
$\frac{\mathrm{x}}{4}$
C.
$4\mathrm{x}$
D.
$2\mathrm{x}$
Q94 Allen MEASURING DEVICES MCQ
In the following circuit, the resistance of the voltmeter is 10,000 Ω and that of the ammeter is 20 Ω. If the reading of the ammeter is 0.1 A and that of the voltmeter is 12 V, then the value of R is :-
A.
$122\Omega$
B.
$100\Omega$
C.
$118\Omega$
D.
$116\Omega$
Q95 Allen MEASURING DEVICES MCQ
The resistance of a galvanometer is G ohms and the range is 1 volt. The value of resistance (in $\Omega$ ) used to convert it into a voltmeter of range 10 volts is :-
A.
9 G
B.
G
C.
$\frac{1}{9}$ G
D.
10 G
Q96 Allen MEASURING DEVICES MCQ
A galvanometer has 36 Ω resistance. If a 4 Ω shunt is added to this, the fraction of current that passes through the galvanometer is :-
A.
$\frac{1}{4}$
B.
$\frac{1}{9}$
C.
$\frac{1}{10}$
D.
$\frac{1}{40}$
Q97 Allen MEASURING DEVICES MCQ
A galvanometer of resistance 100 Ω gives full deflection for a current of $10^{-5}$ A. The value of shunt required to convert it into an ammeter of range 1 ampere, is :-
A.
1 Ω
B.
$10^{-3}$ Ω
C.
$10^{-5}$ Ω
D.
100 Ω
Q98 Allen MEASURING DEVICES MCQ
There are three voltmeters of the same range but of resistances 10000 Ω, 8000 Ω and 4000 Ω respectively. The best voltmeter among these is the one whose resistance is :-
A.
10000 Ω
B.
8000 Ω
C.
4000 Ω
D.
all are equally good
Q99 Allen MEASURING DEVICES MCQ
20% of the main current passes through the galvanometer. If the resistance of the galvanometer is G, then the resistance of the shunt will be :-
A.
$\frac{G}{50}$
B.
$\frac{G}{4}$
C.
$50G$
D.
$9G$
Q100 Allen MEASURING DEVICES MCQ
An unknown resistance $R_{1}$ is connected in series with a resistance of 10 Ω. This combination is connected to one gap of a metre bridge while a resistance $R_{2}$ is connected in the other gap. The balance point is at 50 cm. Now, when the 10 Ω resistance is removed the balance point shifts to 40 cm. The value of $R_{1}$ is (in ohms) :-
A.
20
B.
10
C.
60
D.
40