Current Electricity- 3 Practice Questions - DPP for NEET

 Page 1


DIRECTIONS (Q.1-Q.16) : There are 16 multiple choice
questions. Each question has 4 choices (a), (b), (c) and (d), out
of which ONLY ONE choice is correct.
Q.1 A Potentiometer wire of length 1 m is connected in series
with 490 W resistance and 2V battery . If 0.2 mV/cm is the
potential gradient, then resistance of the potentiometer
wire is
(a) 4.9 W (b) 7.9 W (c) 5.9 W (d) 6.9 W
Q.2 Two resistances are connected in two gaps of a metre
bridge. The balance point is 20 cm from the zero end. A
resistance of 15 ohms is connected in series with the
smaller of the two. The null point shifts to 40 cm. The
value of the smaller resistance in ohm is
(a)3 (b)6 (c)9 (d) 12
Q.3 In a potentiometer experiment the balancing with a cell is
at length 240 cm. On shunting the cell with a resistance of
2 W, the balancing length becomes 120 cm. The internal
resistance of the cell is
(a) 4 W (b) 2 W (c) 1 W (d) 0.5 W
Q.4 A potentiometer consists of a wire of length 4 m and
resistance 10 W . It is connected to cell of emf 2 V. The
potential difference per unit length of the wire will be
(a) 0.5 V/m (b) 10 V/m (c) 2 V/m (d) 5 V/m
Q.5 In given figure, the potentiometer wire AB has a resistance
of 5 W and length 10 m. The balancing length AM for the
emf of 0.4 V is
(a) 0.4 m
(b) 4 m
(c) 0.8 m
(d) 8 m
Page 2


DIRECTIONS (Q.1-Q.16) : There are 16 multiple choice
questions. Each question has 4 choices (a), (b), (c) and (d), out
of which ONLY ONE choice is correct.
Q.1 A Potentiometer wire of length 1 m is connected in series
with 490 W resistance and 2V battery . If 0.2 mV/cm is the
potential gradient, then resistance of the potentiometer
wire is
(a) 4.9 W (b) 7.9 W (c) 5.9 W (d) 6.9 W
Q.2 Two resistances are connected in two gaps of a metre
bridge. The balance point is 20 cm from the zero end. A
resistance of 15 ohms is connected in series with the
smaller of the two. The null point shifts to 40 cm. The
value of the smaller resistance in ohm is
(a)3 (b)6 (c)9 (d) 12
Q.3 In a potentiometer experiment the balancing with a cell is
at length 240 cm. On shunting the cell with a resistance of
2 W, the balancing length becomes 120 cm. The internal
resistance of the cell is
(a) 4 W (b) 2 W (c) 1 W (d) 0.5 W
Q.4 A potentiometer consists of a wire of length 4 m and
resistance 10 W . It is connected to cell of emf 2 V. The
potential difference per unit length of the wire will be
(a) 0.5 V/m (b) 10 V/m (c) 2 V/m (d) 5 V/m
Q.5 In given figure, the potentiometer wire AB has a resistance
of 5 W and length 10 m. The balancing length AM for the
emf of 0.4 V is
(a) 0.4 m
(b) 4 m
(c) 0.8 m
(d) 8 m
2
DPP/ P 38
Q.6 In the circuit shown in the figure, the current flowing in
2W resistance
(a) 1.4 A
G
10 W
25 W 5 W
2 W
1.4 A
(b) 1.2 A
(c) 0.4 A
(d) 1.0 A
Q.7 For the post office box arrangement to determine the value
of unknown resistance the unknown resistance should be
connected between
(a) B and C (b) C and D (c) A and D (d) B
1
and C
1
Q.8 The e.m.f. of a standard cell balances across 150 cm length
of a wire of potentiometer. When a resistance of 2W is
connected as a shunt with the cell, the balance point is
obtained at 100 cm. The internal resistance of the cell is
(a) 0.1 W (b)1W (c)2W (d) 0.5W
Q.9 Five resistors are connected as shown in the diagram. The
equivalent resistance between A and B is
(a) 6 W 5 W
10 W 8 W
4 W
9 W
A B
C
D
(b) 9 W
(c) 12 W
(d) 15 W
Q.10A potentiometer has uniform potential gradient. The
specific resistance of the material of the potentiometer
wire is 10
–7 
ohm-meter and the current passing through it
is 0.1 ampere; cross-section of the wire is 10
–6
m
2
. The
potential gradient along the potentiometer wire is
(a) 10
–4
 V/m (b) 10
–6
 V/m
(c) 10
–2
 V/m (d) 10
–8
 V/m
Q.11 Resistance in the two gaps of a meter bridge are 10 ohm
and 30 ohm  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
Q.12 A potentiometer has uniform potential gradient across it.
Two cells connected in series (i) to support each other
and (ii) to oppose each other are blanced over 6m and 2m
respectively on the potentiometer wire. The e.m.f’s of the
cells are in the ratio of
(a) 1 : 2 (b) 1 : 1 (c) 3 : 1 (d) 2 : 1
Q.13 In a potentiometer experiment two cells of e.m.f E
1 
and E
2
are used in series and in conjunction and the balancing
length is found to be 58 cm of the wire. If the polarity of
2
E is reversed, then the balancing length becomes 29 cm.
The ratio 
1
2
E
E
of the e.m.f. of the two cells is
(a) 1 : 1 (b) 2 : 1 (c) 3 : 1 (d) 4 : 1
Q.14The resistance of a 10 meter long potentiometer wire is
1 ohm/metre. A cell of e.m.f. 2.2 volts and a high resistance
box are connected in series with this wire. The value of
resistance taken from resistance box for getting potential
gradient of 2.2 millivolt/metre will be
(a) 790 W (b) 810 W (c) 990 W (d) 1000 W
Q.15 In the shown arrangement of the experiment of the meter
bridge if AC corresponding to null deflection of
galvanometer is x, what would be its value if the radius of
the wire AB is doubled
G
x
A C
B
R
2
R
1
(a) x (b)
/4 x
(c)
4x
(d)
2x
Q.16 In meter bridge or Wheatstone bridge for measurement of
resistance, the known and the unknown resistances are
interchanged. The error so removed is
(a) End correction
(b) Index error
(c) Due to temperature effect
(d) Random error
Page 3


DIRECTIONS (Q.1-Q.16) : There are 16 multiple choice
questions. Each question has 4 choices (a), (b), (c) and (d), out
of which ONLY ONE choice is correct.
Q.1 A Potentiometer wire of length 1 m is connected in series
with 490 W resistance and 2V battery . If 0.2 mV/cm is the
potential gradient, then resistance of the potentiometer
wire is
(a) 4.9 W (b) 7.9 W (c) 5.9 W (d) 6.9 W
Q.2 Two resistances are connected in two gaps of a metre
bridge. The balance point is 20 cm from the zero end. A
resistance of 15 ohms is connected in series with the
smaller of the two. The null point shifts to 40 cm. The
value of the smaller resistance in ohm is
(a)3 (b)6 (c)9 (d) 12
Q.3 In a potentiometer experiment the balancing with a cell is
at length 240 cm. On shunting the cell with a resistance of
2 W, the balancing length becomes 120 cm. The internal
resistance of the cell is
(a) 4 W (b) 2 W (c) 1 W (d) 0.5 W
Q.4 A potentiometer consists of a wire of length 4 m and
resistance 10 W . It is connected to cell of emf 2 V. The
potential difference per unit length of the wire will be
(a) 0.5 V/m (b) 10 V/m (c) 2 V/m (d) 5 V/m
Q.5 In given figure, the potentiometer wire AB has a resistance
of 5 W and length 10 m. The balancing length AM for the
emf of 0.4 V is
(a) 0.4 m
(b) 4 m
(c) 0.8 m
(d) 8 m
2
DPP/ P 38
Q.6 In the circuit shown in the figure, the current flowing in
2W resistance
(a) 1.4 A
G
10 W
25 W 5 W
2 W
1.4 A
(b) 1.2 A
(c) 0.4 A
(d) 1.0 A
Q.7 For the post office box arrangement to determine the value
of unknown resistance the unknown resistance should be
connected between
(a) B and C (b) C and D (c) A and D (d) B
1
and C
1
Q.8 The e.m.f. of a standard cell balances across 150 cm length
of a wire of potentiometer. When a resistance of 2W is
connected as a shunt with the cell, the balance point is
obtained at 100 cm. The internal resistance of the cell is
(a) 0.1 W (b)1W (c)2W (d) 0.5W
Q.9 Five resistors are connected as shown in the diagram. The
equivalent resistance between A and B is
(a) 6 W 5 W
10 W 8 W
4 W
9 W
A B
C
D
(b) 9 W
(c) 12 W
(d) 15 W
Q.10A potentiometer has uniform potential gradient. The
specific resistance of the material of the potentiometer
wire is 10
–7 
ohm-meter and the current passing through it
is 0.1 ampere; cross-section of the wire is 10
–6
m
2
. The
potential gradient along the potentiometer wire is
(a) 10
–4
 V/m (b) 10
–6
 V/m
(c) 10
–2
 V/m (d) 10
–8
 V/m
Q.11 Resistance in the two gaps of a meter bridge are 10 ohm
and 30 ohm  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
Q.12 A potentiometer has uniform potential gradient across it.
Two cells connected in series (i) to support each other
and (ii) to oppose each other are blanced over 6m and 2m
respectively on the potentiometer wire. The e.m.f’s of the
cells are in the ratio of
(a) 1 : 2 (b) 1 : 1 (c) 3 : 1 (d) 2 : 1
Q.13 In a potentiometer experiment two cells of e.m.f E
1 
and E
2
are used in series and in conjunction and the balancing
length is found to be 58 cm of the wire. If the polarity of
2
E is reversed, then the balancing length becomes 29 cm.
The ratio 
1
2
E
E
of the e.m.f. of the two cells is
(a) 1 : 1 (b) 2 : 1 (c) 3 : 1 (d) 4 : 1
Q.14The resistance of a 10 meter long potentiometer wire is
1 ohm/metre. A cell of e.m.f. 2.2 volts and a high resistance
box are connected in series with this wire. The value of
resistance taken from resistance box for getting potential
gradient of 2.2 millivolt/metre will be
(a) 790 W (b) 810 W (c) 990 W (d) 1000 W
Q.15 In the shown arrangement of the experiment of the meter
bridge if AC corresponding to null deflection of
galvanometer is x, what would be its value if the radius of
the wire AB is doubled
G
x
A C
B
R
2
R
1
(a) x (b)
/4 x
(c)
4x
(d)
2x
Q.16 In meter bridge or Wheatstone bridge for measurement of
resistance, the known and the unknown resistances are
interchanged. The error so removed is
(a) End correction
(b) Index error
(c) Due to temperature effect
(d) Random error
DPP/ P 38
3
DIRECTIONS (Q.17-Q.19) : In the following questions,
more than one of the answers  given are correct. Select the
correct answ]ers and mark it according to the following
codes:
Codes :
(a) 1, 2 and 3 are correct (b) 1 and 2 are correct
(c) 2 and 4 are correct (d) 1 and 3 are correct
Q.17Which of the following statements are correct?
(1) Voltmeter should have high resistance.
(2) Ammeter should have low resistance.
(3) Voltmeter is placed in parallel across the conductor
in a circuit.
(4) Ammeter is placed in parallel across the conductor
in a circuit.
Q.18Which are correct statements?
(1) The Wheatstone bridge is most sensitive when all the
four resistances are of the same order
(2) Kirchhoff’s first law (for currents meeting at a junction in
an electric circuit) expresses the conservtion of charge.
(3) The rheostat can be used as a potential divider.
(4) In a balanced Wheatstone bridge, interchanging the
positions of galvanometer and cell affects the balance
of the bridge.
Q.19 Figure shows a balanced Wheatstone's bridge
R = 5W
Q = 50W
S = 10W
P = 100W
G
A C
(1) If P is slightly increased, the current in the
galvanometer flows from A to C.
(2) If P is slightly increased, the current in the
galvanometer flows from C to A.
(3) If Q is slightly increased, the current in the
galvanometer flows from C to A.
(4) If Q is slightly increased, the current in the
galvanometer flows from A to C.
DIRECTIONS (Q.20-Q.22) : Read the passage given below
and answer the questions that follows :
A battery is connected to a potentiometer and a balance point is
obtained at 84 cm along the wire. When its terminals are
connected by a 5W resistor, the balance point changes to 70 cm
Q.20Calculate the internal resistance of the cell.
(a) 4 W (b)2W (c) 5 W (d) 1 W
Q.21Find the new position of the balance point when 5W
resistance is replaced by 4W resistor.
(a) 26.5 cm (b) 52 cm (c) 67.2 cm (d) 83.3 cm
Q.22 How can we change a galvanometer with R
e
 = 20.0W and
I
fs
 = 0.00100 A into a voltmeter with a maximum range of
10.0 V?
(a) By adding a resistance 9980 W in parallel with the
galvanometer
(b) By adding a resistance 9980 W in series with the
galvanometer
(c) By adding a resistance 8890 W in parallel with the
galvanometer
(d) By adding a resistance 8890 W in series with the
galvanometer
DIRECTIONS (Q. 23-Q.25) : Each of these questions contains
two statements: Statement-1 (Assertion) and Statement-2
(Reason). Each of these questions has four alternative choices,
only one of which is the correct answer. You have to select the
correct choice.
(a) Statement-1 is True, Statement-2 is True; Statement-2 is a
correct explanation for  Statement-1.
(b) Statement-1 is True, Statement-2 is True; Statement-2 is
NOT a correct explanation for Statement-1.
(c) Statement -1 is False, Statement-2 is True.
(d) Statement -1 is True, Statement-2 is False.
Q.23Statement -1 : In meter bridge experiment, a high
resistance is always connected in series with a
galvanometer.
Statement -2 : As resistance increases current through the
circuit increases.
Page 4


DIRECTIONS (Q.1-Q.16) : There are 16 multiple choice
questions. Each question has 4 choices (a), (b), (c) and (d), out
of which ONLY ONE choice is correct.
Q.1 A Potentiometer wire of length 1 m is connected in series
with 490 W resistance and 2V battery . If 0.2 mV/cm is the
potential gradient, then resistance of the potentiometer
wire is
(a) 4.9 W (b) 7.9 W (c) 5.9 W (d) 6.9 W
Q.2 Two resistances are connected in two gaps of a metre
bridge. The balance point is 20 cm from the zero end. A
resistance of 15 ohms is connected in series with the
smaller of the two. The null point shifts to 40 cm. The
value of the smaller resistance in ohm is
(a)3 (b)6 (c)9 (d) 12
Q.3 In a potentiometer experiment the balancing with a cell is
at length 240 cm. On shunting the cell with a resistance of
2 W, the balancing length becomes 120 cm. The internal
resistance of the cell is
(a) 4 W (b) 2 W (c) 1 W (d) 0.5 W
Q.4 A potentiometer consists of a wire of length 4 m and
resistance 10 W . It is connected to cell of emf 2 V. The
potential difference per unit length of the wire will be
(a) 0.5 V/m (b) 10 V/m (c) 2 V/m (d) 5 V/m
Q.5 In given figure, the potentiometer wire AB has a resistance
of 5 W and length 10 m. The balancing length AM for the
emf of 0.4 V is
(a) 0.4 m
(b) 4 m
(c) 0.8 m
(d) 8 m
2
DPP/ P 38
Q.6 In the circuit shown in the figure, the current flowing in
2W resistance
(a) 1.4 A
G
10 W
25 W 5 W
2 W
1.4 A
(b) 1.2 A
(c) 0.4 A
(d) 1.0 A
Q.7 For the post office box arrangement to determine the value
of unknown resistance the unknown resistance should be
connected between
(a) B and C (b) C and D (c) A and D (d) B
1
and C
1
Q.8 The e.m.f. of a standard cell balances across 150 cm length
of a wire of potentiometer. When a resistance of 2W is
connected as a shunt with the cell, the balance point is
obtained at 100 cm. The internal resistance of the cell is
(a) 0.1 W (b)1W (c)2W (d) 0.5W
Q.9 Five resistors are connected as shown in the diagram. The
equivalent resistance between A and B is
(a) 6 W 5 W
10 W 8 W
4 W
9 W
A B
C
D
(b) 9 W
(c) 12 W
(d) 15 W
Q.10A potentiometer has uniform potential gradient. The
specific resistance of the material of the potentiometer
wire is 10
–7 
ohm-meter and the current passing through it
is 0.1 ampere; cross-section of the wire is 10
–6
m
2
. The
potential gradient along the potentiometer wire is
(a) 10
–4
 V/m (b) 10
–6
 V/m
(c) 10
–2
 V/m (d) 10
–8
 V/m
Q.11 Resistance in the two gaps of a meter bridge are 10 ohm
and 30 ohm  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
Q.12 A potentiometer has uniform potential gradient across it.
Two cells connected in series (i) to support each other
and (ii) to oppose each other are blanced over 6m and 2m
respectively on the potentiometer wire. The e.m.f’s of the
cells are in the ratio of
(a) 1 : 2 (b) 1 : 1 (c) 3 : 1 (d) 2 : 1
Q.13 In a potentiometer experiment two cells of e.m.f E
1 
and E
2
are used in series and in conjunction and the balancing
length is found to be 58 cm of the wire. If the polarity of
2
E is reversed, then the balancing length becomes 29 cm.
The ratio 
1
2
E
E
of the e.m.f. of the two cells is
(a) 1 : 1 (b) 2 : 1 (c) 3 : 1 (d) 4 : 1
Q.14The resistance of a 10 meter long potentiometer wire is
1 ohm/metre. A cell of e.m.f. 2.2 volts and a high resistance
box are connected in series with this wire. The value of
resistance taken from resistance box for getting potential
gradient of 2.2 millivolt/metre will be
(a) 790 W (b) 810 W (c) 990 W (d) 1000 W
Q.15 In the shown arrangement of the experiment of the meter
bridge if AC corresponding to null deflection of
galvanometer is x, what would be its value if the radius of
the wire AB is doubled
G
x
A C
B
R
2
R
1
(a) x (b)
/4 x
(c)
4x
(d)
2x
Q.16 In meter bridge or Wheatstone bridge for measurement of
resistance, the known and the unknown resistances are
interchanged. The error so removed is
(a) End correction
(b) Index error
(c) Due to temperature effect
(d) Random error
DPP/ P 38
3
DIRECTIONS (Q.17-Q.19) : In the following questions,
more than one of the answers  given are correct. Select the
correct answ]ers and mark it according to the following
codes:
Codes :
(a) 1, 2 and 3 are correct (b) 1 and 2 are correct
(c) 2 and 4 are correct (d) 1 and 3 are correct
Q.17Which of the following statements are correct?
(1) Voltmeter should have high resistance.
(2) Ammeter should have low resistance.
(3) Voltmeter is placed in parallel across the conductor
in a circuit.
(4) Ammeter is placed in parallel across the conductor
in a circuit.
Q.18Which are correct statements?
(1) The Wheatstone bridge is most sensitive when all the
four resistances are of the same order
(2) Kirchhoff’s first law (for currents meeting at a junction in
an electric circuit) expresses the conservtion of charge.
(3) The rheostat can be used as a potential divider.
(4) In a balanced Wheatstone bridge, interchanging the
positions of galvanometer and cell affects the balance
of the bridge.
Q.19 Figure shows a balanced Wheatstone's bridge
R = 5W
Q = 50W
S = 10W
P = 100W
G
A C
(1) If P is slightly increased, the current in the
galvanometer flows from A to C.
(2) If P is slightly increased, the current in the
galvanometer flows from C to A.
(3) If Q is slightly increased, the current in the
galvanometer flows from C to A.
(4) If Q is slightly increased, the current in the
galvanometer flows from A to C.
DIRECTIONS (Q.20-Q.22) : Read the passage given below
and answer the questions that follows :
A battery is connected to a potentiometer and a balance point is
obtained at 84 cm along the wire. When its terminals are
connected by a 5W resistor, the balance point changes to 70 cm
Q.20Calculate the internal resistance of the cell.
(a) 4 W (b)2W (c) 5 W (d) 1 W
Q.21Find the new position of the balance point when 5W
resistance is replaced by 4W resistor.
(a) 26.5 cm (b) 52 cm (c) 67.2 cm (d) 83.3 cm
Q.22 How can we change a galvanometer with R
e
 = 20.0W and
I
fs
 = 0.00100 A into a voltmeter with a maximum range of
10.0 V?
(a) By adding a resistance 9980 W in parallel with the
galvanometer
(b) By adding a resistance 9980 W in series with the
galvanometer
(c) By adding a resistance 8890 W in parallel with the
galvanometer
(d) By adding a resistance 8890 W in series with the
galvanometer
DIRECTIONS (Q. 23-Q.25) : Each of these questions contains
two statements: Statement-1 (Assertion) and Statement-2
(Reason). Each of these questions has four alternative choices,
only one of which is the correct answer. You have to select the
correct choice.
(a) Statement-1 is True, Statement-2 is True; Statement-2 is a
correct explanation for  Statement-1.
(b) Statement-1 is True, Statement-2 is True; Statement-2 is
NOT a correct explanation for Statement-1.
(c) Statement -1 is False, Statement-2 is True.
(d) Statement -1 is True, Statement-2 is False.
Q.23Statement -1 : In meter bridge experiment, a high
resistance is always connected in series with a
galvanometer.
Statement -2 : As resistance increases current through the
circuit increases.
4
DPP/ P 38
Q.24 Statement -1: A potentiometer of longer length is used
for accurate measurement.
Statement -2: The potential gradient for a potentiometer
of longer length with a given source of e.m.f. becomes
small.
Q.25Statement -1: The e.m.f. of the driver cell in the
potentiometer experiment should be greater than the e.m.f.
of the cell to be determined.
Statement -2: The fall of potential across the
potentiometer wire should not be less than the e.m.f. of
the cell to be determined.