Q126
Allen
PYQ
MCQ
The equivalent resistance between A and B for the mesh shown in the figure is
A.
$7.2\Omega$
B.
$16\Omega$
C.
$30\Omega$
D.
$4.8\Omega$
Q127
Allen
PYQ
MCQ
Two solid conductors are made up of same material, have same length and same resistance. One of them has a circular cross section of area $A_{1}$ and the other one has a square cross section of area $A_{2}$ . The ratio $A_{1}/A_{2}$ is
A.
1.5
B.
1
C.
0.8
D.
2
Q128
Allen
PYQ
Match the Columns
gives certain physical terms associated with flow of current through a metallic conductor. gives some mathematical relations involving electrical quantities. Match and with appropriate relations.
| Column-I | Column-II | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|
A.
(A)-(R), (B)-(S), (C)-(P), (D)-(Q)
B.
(A)-(R), (B)-(S), (C)-(Q), (D)-(P)
C.
(A)-(R), (B)-(P), (C)-(S), (D)-(Q)
D.
(A)-(R), (B)-(Q), (C)-(S), (D)-(P)
Q129
Allen
PYQ
MCQ
The effective resistance of a parallel connection that consists of four wires of equal length, equal area of cross-section and same material is 0.25 Ī©. What will be the effective resistance if they are connected in series?
A.
0.25 Ī©
B.
0.5 Ī©
C.
1 Ī©
D.
4Ī©
Q130
Allen
PYQ
MCQ
Three resistors having resistances $r_{1}$ , $r_{2}$ and $r_{3}$ are connected as shown in the given circuit. The ratio $\frac{i_{3}}{i_{1}}$ of currents in terms of resistances used in the circuit is :
A.
$\frac{\mathrm{r}_1}{\mathrm{r}_2 + \mathrm{r}_3}$
B.
$\frac{\mathrm{r}_2}{\mathrm{r}_2 + \mathrm{r}_3}$
C.
$\frac{\mathrm{r}_1}{\mathrm{r}_1 + \mathrm{r}_2}$
D.
$\frac{\mathrm{r}_2}{\mathrm{r}_1 + \mathrm{r}_3}$
Q131
Allen
PYQ
MCQ
Two hollow conducting spheres of radii $R_{1}$ and $R_{2}$ ( $R_{1} >> R_{2}$ ) have equal charges. The potential would be :
A.
more on smaller sphere
B.
equal on both the spheres
C.
dependent on the material property of the sphere
D.
more on bigger sphere
Q132
Allen
PYQ
MCQ
Two resistors of resistance, 100 $\Omega $ and 200 $\Omega $
are connected in parallel in an electrical
circuit. The ratio of the thermal energy
developed in 100 $\Omega $ to that in 200 $\Omega $ in a given
time is :
A.
2 : 1
B.
1 : 4
C.
4 : 1
D.
1 : 2
Q133
Allen
PYQ
MCQ
As the temperature increase, the electrical resistance:
A.
decreases for both conductors and semiconductors
B.
increases for conductors but decreases for semiconductors
C.
decreases for conductors but increase for semiconductors
D.
increases for both conductors and semiconductors.
Q134
Allen
PYQ
MCQ
A copper wire of length 10 m and radius $\left(10^{-2}/\sqrt{\pi}\right)$ m has electrical resistance of 10 Ī©. The current density in the wire for an electric field strength of 10 (V/m) is:
A.
$10^{6}$ A/m $^{2}$
B.
$10^{-5}$ A/m $^{2}$
C.
$10^{5}$ A/m $^{2}$
D.
$10^{4}$ A/m $^{2}$
Q135
Allen
PYQ
MCQ
A wheatstone bridge is used to determine the value of unknown resistance X by adjusting the variable resistance Y as shown in the figure. For the most precise measurement of X, the resistances P and Q :
A.
should be approximately equal and are small
B.
should be very large and unequal
C.
do not play any significant role
D.
should be approximately equal to 2X
Q136
Allen
PYQ
MCQ
A cell of emf 4 V and internal resistance 0.5 Ī© is connected to a 7.5 Ī© external resistance. The terminal potential difference of the cell is :
A.
3.75 V
B.
4.25 V
C.
4 V
D.
0.375 V
Q137
Allen
PYQ
MCQ
The equivalent resistance of the infinite network given below is :
A.
$2\Omega$
B.
$(1 + \sqrt{2})\Omega$
C.
$(1 + \sqrt{3})\Omega$
D.
$(1 + \sqrt{5})\Omega$
Q138
Allen
PYQ
MCQ
The reciprocal of resistance is:
A.
reactance
B.
mobility
C.
conductivity
D.
conductance
Q139
Allen
PYQ
MCQ
The sliding contact C is at one fourth of the length of the potentiometer wire (AB) from A as shown in the circuit diagram. If the resistance of the wire AB is $R_{0}$ , then the potential drop (V) across the resistor R is:
A.
$\frac{4\mathrm{V}_0\mathrm{R}}{3\mathrm{R}_0 + 16\mathrm{R}}$
B.
$\frac{4\mathrm{V}_0\mathrm{R}}{3\mathrm{R}_0 + \mathrm{R}}$
C.
$\frac{2\mathrm{V}_0\mathrm{R}}{4\mathrm{R}_0 + \mathrm{R}}$
D.
$\frac{2\mathrm{V}_0\mathrm{R}}{2\mathrm{R}_0 + 3\mathrm{R}}$
Q140
Allen
PYQ
MCQ
The magnitude and direction of the current in the following circuit is :-
A.
0.5 A from A to B through E
B.
$\frac{5}{9}$ A from A to B through E
C.
1.5 A from B to A through E
D.
0.2 A from B to A through E
Q141
Allen
PYQ
MCQ
If the galvanometer G does not show any deflection in the circuit shown, the value of R is given by :
A.
$50\Omega$
B.
$100\Omega$
C.
$400\Omega$
D.
$200\Omega$
Q142
Allen
PYQ
MCQ
The resistance of platinum wire at $0^{\circ}C$ is $2\Omega$ and $6.8\Omega$ at $80^{\circ}C$ . The temperature coefficient of resistance of the wire is:
A.
$3 \times 10^{-3} \, ^{\circ}C^{-1}$
B.
$3 \times 10^{-2} \, ^{\circ}C^{-1}$
C.
$3 \times 10^{-1} \, ^{\circ}C^{-1}$
D.
$3 \times 10^{-4} \, ^{\circ}C^{-1}$
Q143
Allen
PYQ
MCQ
10 resistors, each of resistance R are connected in series to a battery of emf E and negligible internal resistance. Then those are connected in parallel to the same battery, the current is increased n times. The value of n is: -
A.
100
B.
1
C.
1000
D.
10
P
P
Q144
Allen
PYQ
MCQ
A certain wire A has resistance 81 Ī©. The resistance of another wire B of same material and equal length but of diameter thrice the diameter of A will be:
A.
81 Ī©
B.
9 Ī©
C.
729 Ī©
D.
243 Ī©
Q145
Allen
PYQ
MCQ
A copper wire of radius 1 mm contains $10^{22}$ free electrons per cubic metre. The drift velocity for free electrons when 10 A current flows through the wire will be (Given, charge on electron = $1.6 \times 10^{-19}$ C):
A.
$\frac{6.25 \times 10^{4}}{\pi} ms^{-1}$
B.
$\frac{6.25}{\pi} \times 10^{3} ms^{-1}$
C.
$\frac{6.25}{\pi} ms^{-1}$
D.
$\frac{6.25 \times 10^{5}}{\pi} ms^{-1}$
Q146
Allen
PYQ
MCQ
The terminal voltage of the battery, whose emf is 10V and internal resistance 1Ī©, when connected through an external resistance of 4Ī© as shown in the figure.
A.
4V
B.
6V
C.
8V
D.
10V
Q147
Allen
PYQ
MCQ
A wire of length ' $\ell'$ and resistance 100 $\Omega$ is divided into 10 equal parts. The first 5 parts are connected in series while the next 5 parts are connected in parallel. The two combinations are again connected in series. The resistance of this final combination is:
A.
26 $\Omega$
B.
52 $\Omega$
C.
55 $\Omega$
D.
60 $\Omega$
Q148
Allen
PYQ
MCQ
Two heaters A and B have power rating of 1 kW and 2 kW, respectively. Those two are first connected in series and then in parallel to a fixed power source. The ratio of power outputs for these two cases is:
A.
1:1
B.
2:9
C.
1:2
D.
2:3
Q149
Allen
PYQ
MCQ
A uniform wire of diameter d carries a current of 100 mA when the mean drift velocity of electrons in the wire is v. For a wire of diameter $\frac{d}{2}$ of the same material to carry a current of 200 mA, the mean drift velocity of electrons in the wire is:
A.
4 v
B.
8 v
C.
v
D.
2 v
Q150
Allen
PYQ
MCQ
A uniform metal wire of length $\ell$ has $10\Omega$ resistance. Now this wire is stretched to a length $2\ell$ and then bent to form a perfect circle. The equivalent resistance across any arbitrary diameter of that circle is:
A.
$10\Omega$
B.
$5\Omega$
C.
$40\Omega$
D.
$20\Omega$
