Download Circuits

AL-MC-Circuits / p.1
1.
(88-I-29)
A.
(1), (2) and (3)
Which of the following is/are equivalent to a unit
B.
(1) and (2) only
of energy?
C.
(2) and (3) only
D.
(1) only
E.
(3) only
(1)
electron-volt
(2)
kilowatt-hour
(3)
volt-coulomb
4.
(88-I-40)
A.
(1), (2) and (3)
B.
(1) and (2) only
C.
(2) and (3) only
D.
(1) only
If the pattern shown above appears on the CRO
E.
(3) only
screen when two sinusoidal a.c. voltages are
applied across the x-plates and the y-plates, what is
2.
(88-I-30)
the ratio of the frequency of the voltage across the
x-plates to that across the y-plates?
A.
1:4
B.
1:2
C.
1:1
Four particles carrying charges +q, +q, –2q and
D.
2:1
–2q are placed at the vertices of a square of side a.
E.
4:1
The electric potential at the centre of the square is
5.
A.
zero.
B.
 2q /( 2  0 a).
C.
 2q /(  0 a).
D.
 2q /( 2  0 a).
E.
 2q /(  0 a).
(89-I-28)
In the above circuit, V is a voltmeter of high
internal resistance and A is an ammeter of low
internal resistance. What is the voltmeter reading
when (a) switch K is open, (b) switch K is closed?
3.
(88-I-32)
If a metal conductor, of cross-sectional area A, has
K open
K closed
A.
0V
0V
B.
0V
2V
n free electrons per unit volume, each carrying a
charge e and moving with a drift velocity v, the
(1)
current density will be n ev.
C.
1V
1V
(2)
Current flowing will be ev A.
D.
2V
0V
(3)
Drift velocity will increase with temperature.
E.
2V
2V
AL-MC-Circuits / p.2
6.
(89-I-29)
9.
A.
0V
B.
1V
C.
2V
D.
3V
E.
4V
(90-I-33)
In the above circuit, the equivalent resistance
between A and B is
7.
A.
2/7  .
B.
2/5  .
In the above circuit, the battery has negligible
C.
2/3  .
internal resistance. The current I is
D.
2 .
E.
5 .
(89-I-31)
10.
A.
2/3 A.
B.
1 A.
C.
4/3 A.
D.
2 A.
E.
6 A.
(90-I-34)
Which of the following circuits is best used for the
measurement of a low resistance R?
In the above circuit, AB is a metre-wire of
(Polarities of meter terminals are given in the
resistance 10  . When X is moved to the
diagram.)
mid-point of AB, the p.d. across AX will be
8.
A.
2.5 V.
B.
4.0 V.
C.
5.0 V.
D.
6.0 V.
E.
7.5 V.
(90-I-32)
The figure above shows part of a circuit which
carries a current of 1 A from X to Y through a cell of
e.m.f. 3 V and internal resistance 1  . The potential
difference between X and Y is
AL-MC-Circuits / p.3
11.
(90-I-35)
13.
(90-I-42)
In the potentiometer circuit shown, S is a source
whose e.m.f. is to be measured. R is a resistor to
protect the galvanometer G. In the experiment, a
Two sinusoidal alternating potential differences
student finds that G deflects in the same direction
VX and V y of the same frequency are applied
for any position of C, giving maximum deflection
at B and minimum deflection (not zero) at A.
respectively to the x and y plates of a C.R.O. with
Which of the following is the possible reason?
the time base switched off. The trace on the screen
is an ellipse as shown above. What is the phase
A.
S is connected with wrong polarity.
B.
The resistance of R is too high.
C.
There is contact resistance at A and B.
A.
D.
The e.m.f. of the driver cell E is too
B.
low.
C.
The driver cell E has a large internal
D.
resistance.
E.
E.
12. (90-I-40)
difference between
14.
VX and V y ?
30 o
45 o
60 o
120 o
150 o
(90-I-43)
Electrical power is transmitted at high voltage over
long distances because
(1)
a larger amount of energy can be transmitted
per unit charge.
(2)
a smaller current is required for a fixed
amount of power delivered.
(3)
Potential differences
V1 and V2 are applied to the
less power is lost through heating during
X-plates and Y-plates of a C.R.O respectively. The
transmission.
trace on the screen is
A. (1), (2) and (3)
B. (1) and (2) only
C. (2) and (3) only
D. (1) only
E. (3) only
AL-MC-Circuits / p.4
15.
(91-I-32)
A.
25 Hz
B.
50 Hz
C.
100 Hz
D.
200 Hz
E.
400 Hz
17. (92-I-29)
In the circuit shown, filament lamps
L1 and L2
are identical and are seen to be marked ‘6 V 18 W’.
Which of the following statements is/are correct?
(1)
When switch S is closed, lamp
lamp
(2)
L1 and
L2 glow with the same brightness.
When switch S is closed, lamp
L2 glows
with its normal brightness.
(3)
When switch S is opened, lamp
L1 glows
In the circuit shown above, the galvanometer G
reading is zero. So X has a resistance of
A.
15 
B.
25 
C.
50 
D.
100 
E.
150 
with its normal brightness.
18. (92-I-43)
A.
(1), (2) and (3)
B.
(1) and (2) only
C.
(2) and (3) only
D.
(1) only
E.
(3) only
A.C. voltage of frequencies
16. (91-I-42)
applied to the x-plates and y-plates of a CRO
A.C. voltage of frequencies
f1 and f 2 were
applied to the x-plates and y-plates of a cathode ray
respectively. The trace observed is shown above.
f1 : f 2 is equal to
oscilloscope, respectively. The resulting observed
trace is :
If the frequency of
frequency of
f1 and f 2 are
f2 ?
f1 is 100 Hz, what is the
A.
1:3
B.
2:3
C.
1:1
D.
3:2
E.
3:1
AL-MC-Circuits / p.5
19. (93-I-31)
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
21. (93-I-38)
Two cells X and Y, each of internal resistance 3  ,
are connected with tow 6  resistors as shown in
the above circuit.
If cell X has e.m.f. 12 V and the galvanometer G
shows null deflection, what is the e.m.f. of cell Y?
Potential differences
V1 and V2 are applied to
the X-plates and Y-plates of a CRO respectively.
20.
A.
3.0 V
B.
4.0 V
C.
4.8 V
D.
6.0 V
E.
7.2 V
The trace on the screen is
(93-I-34)
The figure above shows a potentiometer circuit
used for measuring the e.m.f.s of cells. The
22. (94-IIA-26)
potential gradient along the potentiometer wire PQ
Two sinusoidal a.c. signals having a phase difference
is assumed to be constant. Which of the following
of 90 are applied to the x-plates and y-plates of a
CRO. Which of the following traces may appear on
statements is/are true?
o
the screen of the CRO?
(1)
If the balance point X is close to P, the
resistance of
(2)
(3)
R1 should be decreased.
At balance, it is better to have point X near
the centre of PQ.
A.
(1) only
At balance, there is no current flowing
B.
(3) only
through the path PABX.
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
AL-MC-Circuits / p.6
23. (94-IIA-29)
26. (95-IIA-31)
In the above circuit, the galvanometer G reads zero.
The resistance of resistor X is
In the above circuit. PQ is a uniform resistance
wire connected to a 12 V constant voltage source.
A.
40  (5/2) 
B.
40  (4/3) 
C.
40  (2/5) 
D.
40  (3/4) 
E.
40  (7/5) 
L1 and L2 are two identical light bulbs, each of
rating 12 V, 8 W. What is the power dissipated by
L1 when the sliding contact J is at the mid-point
of PQ?
24. (95-IIA-23)
Two cells of negligible internal resistance are
A.
1W
B.
2W
C.
4W
D.
6W
E.
8W
27. (95-IIA-42)
connected with two resistors as shown. What is the
The diagram below shows the trace on the screen of
potential difference between X and Y?
a CRO when a sinusoidal signal of frequency 75 Hz
was applied to the Y-plates.
A.
1.33 V
B.
1.67 V
C.
2.00 V
D.
2.33 V
E.
2.67 V
What time base, in ms per division, was the CRO
25. (95-IIA-25)
set at?
A 1 F capacitor, which is initially charged, is
discharged through a 50  resistor. The maximum
A.
1
current during discharge is 100 A. What is the initial
B.
2
charge on the capacitor?
C.
5
D.
10
E.
20
A.
B.
C.
D.
E.
3
5  10 C
1  10 4 C
5  10 4 C
1  10 3 C
2  10 6 C
AL-MC-Circuits / p.7
28. (96-IIA-24)
(2)
the number of conduction electrons per unit
volume
(3)
the speed of the electrical signal
A.
(1) only
B.
(3) only
In the above circuit, the galvanometer reading is
C.
(1) and (2) only
zero. If both cells have negligible internal
D.
(2) and (3) only
resistance, the e.m.f. of the cell E is
E.
(1), (2) and (3)
A.
6V
31. (97-IIA-25)
B.
7V
Two cylindrical metal rods, X and Y, are made from
C.
8V
the same material and have the same mass. The
D.
9V
length of X is three times that of Y. If currents of 1 A
E.
10 V
and 2 A pass through X and Y respectively, the ratio
of the power dissipation in X to that in Y is
29. (96-IIA-25)
Six wires, each of resistance 1  , are joined to form
A.
9:1
a regular tetrahedron ABCD. A current of 2 A flows
B.
1:4
across the tetrahedron at A and B.
C.
9:2
D.
3:4
E.
9:4
32. (97-IIA-29)
Which of the following statements is/are correct?
(1)
Points C and D are of the same potential.
(2)
The current in wire AC is 0.5 A.
(3)
The potential drop across AB is 1 V.
A cell of e.m.f. 1.5 V is connected in series with a
A. (1) only
variable resistor of resistance R and an ammeter A
B. (3) only
of resistance 0.5  . By varying R, series of
C. (1) and (2) only
D. (2) and (3) only
E. (1), (2) and (3)
ammeter readings, I, are taken and a graph of
against R is plotted. The value of the y-intercept is
1
30. (97-IIA-21)
found to be 0.88 A . What is the internal resistance
of the cell?
Which of the following quantities can be increased
A.
0.59 
B.
0.82 
the average drift velocity of the conduction
C.
1.14 
electrons
D.
1.20 
E.
1.32 
by increasing the voltage across a metal wire?
(1)
1
I
AL-MC-Circuits / p.8
33. (97-IIA-33)
35.
(98-IIA-19)
Only a small fraction of the electrical energy
supplied to a light bulb is converted into light energy.
Which of the following explanations is/are correct?
(1)
Energy is absorbed by the glass wall of the
bulb.
(2)
(3)
The resistance of the filament of the bulb is
very high.
The variation of current with the voltage applied
Most of the energy is emitted as infra-red
across a device is as shown. What is the change in
radiation.
resistance of the device when the voltage increases
from 1.0 V and 2.0 V?
A.
(1) only
B.
(3) only
A.
It decreases by 0.25 
C.
(1) and (2) only
B.
It increases by 0.25 
D.
(2) and (3) only
C.
It decreases by 1.50 
E.
(1), (2) and (3)
D.
It increases by 0.60 
E.
It decreases by 0.60 
34. (98-IIA-18)
36. (98-IIA-21)
In the above circuit, light bulbs
L1 , L2 and L3
consume power at the rate 1 : 1 : 3. If the
resistance of
L3 is R , the resistance of L1 is
In the above circuit each cell has negligible
internal resistance. The voltmeter has a resistance
of 5 k  . The reading on the voltmeter is
A.
3R 16
B.
R4
A.
0V
B.
1.0 V
C.
3R 4
C.
1.2 V
D.
1.5 V
D.
4R 9
E.
2.0 V
E.
3R
AL-MC-Circuits / p.9
37. (98-IIA-38)
38.
(98-IIA-39)
In the above circuit, the resistors are identical, the
In a cathode ray tube, the beam of electrons from
battery has negligible internal resistance and the
the electron gun is deflected vertically when a p.d is
voltmeter draws negligible current. What are the
applied between the deflection plates, P and Q, of
possible voltmeter readings before and after closing
length L and separation d. Which of the following
switch S?
changes will increase the deflection of the beam for
a given p.d. across the deflection plates?
(1)
(2)
(3)
S open
S closed
Reducing the p.d. V between the filament
A.
2V
4V
and the anode.
B.
2V
2V
Reducing the separation d between the
C.
0V
4V
deflection plates.
D.
4V
0V
Reducing the length L of the deflection
E.
4V
2V
plates.
39.
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
(99-IIA-16)
The above circuit can be used to find the resistance
of the resistor R. Which of the following
statements is/are correct?
(1)
The current passing through the ammeter is
in fact larger than that passing through R.
(2)
The ratio of voltmeter reading to ammeter
reading is in fact smaller than the resistance
R.
(3)
The circuit is suitable for measuring high
resistance.
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
AL-MC-Circuits / p.10
40.
(99-IIA-17)
42.
(99-IIA-20)
Three resistors of resistance R 1 , R 2 and R 3 are
Each of the following three students states a
connected in parallel. It is known that R 1 >R 2 >R 3 .
conclusion after learning the formulae P = IV, P =
The equivalent resistance of this combination is R.
Which of the following statements is/are correct?
V 2 /R and P = I 2 R in electricity. Which of these
conclusion is/are correct?
(1) Energy dissipated in moving 1 C of charge
(1) The power dissipated by any electric appliance
through the resistor of resistance R 1 is greater
can be calculated from
than that through R 3
P = IV
(2) The power dissipated by a kettle in inversely
proportional to its resistance as P = V 2 /R.
(3) The power consumed by a running motor
(2) R is smaller than R 2
(3) If the resistor with resistance R 1 is removed,
cannot be calculated from
P=I2 R
the resulting equivalent resistance is increased.
(1) only
A.
(1) only
B.
(3) only
B.
(3) only
C.
(1) and (2) only
C.
(1) and (2) only
D.
(2) and (3) only
D.
(2) and (3) only
E.
(1), (2) and (3)
E.
(1), (2) and (3)
43.
41.
A.
(99-IIA-19)
(99-IIA-23)
A resistance wire is connected across the terminals
of a battery. Which of the following statements is
incorrect?
A.
Before connection to the battery, the
conduction electrons in the wire move
randomly.
B.
In the above circuit, the battery has constant e.m.f.
and negligible internal resistance. If switch S is
After connection to the battery, an electric
field is set up along the length of the wire.
C.
The conduction electrons in the wire are
closed, what would happen to the electric potential
accelerated momentarily in the opposite
at P and at Q?
direction to that of the electric field.
D.
Potential at P
Potential at Q
another, giving out heat energy.
E.
A.
increased
increased
B.
increased
decreased
C.
unchanged
unchanged
D.
decreased
increased
E.
decreased
decreased
The conduction electrons collide with one
The current in the wire is proportional to the
average drift velocity of the electrons.
AL-MC-Circuits / p.11
44.
(99-IIA-41)
A.
0.2 A from right to left
B.
0.2 A from left to right
applied in pairs to the X- and Y- inputs of a CRO
C.
0.4 A from right to left
and the resulting Lissajous figures are as shown.
D.
0.4 A from left to right
E.
It cannot be determined as the value of
Three sinusoidal signals V 1 , V 2 and V 3 are
R is not given.
46.
(00-IIA-24)
In the above circuit, the internal resistance of the
If V1 and V2 are applied to the X- and Y- inputs
battery is 4  . R is a variable resistor. Which of
respectively, the Lissajous figure should look like
the following statements about the circuit is/are
correct?
(1)
If the resistance of R is very small, the
terminal potential difference of the battery is
very small but the power dissipated in the
battery is large.
(2)
If the resistance of R is very large, the
current in the circuit is very small but most
of the power supplied by the battery is
dissipated by R.
(3)
If the resistance of R is 4  , the power
supplied to R by the battery is at a maximum.
45.
(00-IIA-23)
The figure shows some of the resistors in a
network of resistors. The magnitudes and
directions of some of the currents are marked as
shown. Find the magnitude and direction of the
current passing through the resistor R.
A.
B.
(1) only
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
AL-MC-Circuits / p.12
47.
(01-IIA-21)
49.
(01-IIA-31)
Which of the following waveforms CANNOT be
obtained by applying sinusoidal voltages to both
X-and Y-inputs of a CRO?
The above figure shows a network of resistors. If a
voltage of 100 V is applied across terminals A and
B, the potential difference between C and D is 80V.
If the voltage is applied across terminals C and D
instead, what is the potential difference between A
and B?
A.
80 V
B.
60 V
C.
40 V
D.
20 V
E.
It cannot be found as the value of R is
50.
(02-IIA-24)
not known
48.
(01-IIA-22)
X and Y are bulbs with ratings ‘ 6V, 12 W ’ and
In the above circuit, the d.c. supply has an e.m.f of
‘ 6V, 3 W’ respectively. If they are connected to a
9 V and its internal resistance is negligible. V1, V2
12 V supply of negligible internal resistance, which
and V3 are three voltmeters with the same finite
of the following connections allows the two bulbs
internal resistance. If V1 reads 4V, find the reading
to work at their respective rated values?
of V3 and the potential difference across resistor R.
Voltmeter reading of V2
P.d. across R
A.
3V
1V
B.
5V
1V
C.
1V
5V
D.
1V
3V
AL-MC-Circuits / p.13
51.
(02-IIA-25)
52.
(03-IIB-25)
A d.c. supply of constant e.m.f. and internal
resistance is connected to a variable resistor of
resistance R. Which of the following graphs best
shows how the total power P delivered by the
supply varies with R?
A.
In the above circuit, a battery of e.m.f. 6V and
negligible internal resistance is connected to three
resistors. What are the electric potentials at P
before and after switch S is closed?
B.
A.
B.
C.
D.
C.
53.
Before
+6 V
+3 V
+2 V
+2 V
After
+3 V
+3 V
+2 V
+3 V
(03-IIB-27)
D.
In the above circuit, the battery has constant e.m.f.
and negligible internal resistance. A high-resistance
voltmeter connected across terminals a and b reads
4 V. If a low-resistance ammeter is connected
across a and b, the ammeter should read
A.
B.
C.
D.
0.6 A
1.0 A
1.2 A
2.0 A
AL-MC-Circuits / p.14
54.
(04-IIA-19)
56.
(04-IIA-21)
The resistance of a reverse-biased diode is to be
determined by the ammeter-voltmeter method
using moving-coil meters. Which of the following
circuits is correctly connected?
The graph shows the I-V characteristic of two light
55.
(04-IIA-20)
bulbs X and Y, which are marked respectively as
‘200 V,100 W’ and ‘200 V, 60 W’. If X and Y are
connected in series to a 200 V mains supply, what
is the approximate power dissipated in each bulb?
X
Y
In the above network of resistors, the resistance of
A.
12W
36W
S is infinitely large and the two resistors R are
B.
15W
25W
identical. If the equivalent resistance across CD is
C.
40W
20W
2.5 K, what is the equivalent resistance across
D.
50W
30W
AC?
A.
2.5 K
B.
3.5 K
C.
5.0 K
D.
infinitely large
57.
(04-IIA-22)
In the above circuit the battery has an e.m.f. of 6V
and internal resistance 2. S is a standard load
resistor of 6 and R is a rheostat. What will the
setting of R be if the power delivered by the battery
to the load resistor S is at a maximum?
A.
0
B.
2
C.
4
D.
6
AL-MC-Circuits / p.15
58.
(04-IIA-23)
A.
100 k

A basic meter of 100 A full-scale deflection and 1
B.
50 k
k internal resistance is converted into a d.c.
C.
25 k
voltmeter of 5V full-scale deflection. What is the
D.
5 k
internal resistance of this voltmeter?
59.
(05-IIA-17)