JEE Questions for Physics Current Electricity I Quiz 6 - MCQExams.com

A moving coil galvanometer has a resistance of 10 and full scale deflection of 0.01 A. It can be converted into voltmeter of 10V full scale by connecting into resistance of
  • 9.90 Ω in series
  • 10 Ω in series
  • 990 Ω in series
  • 0.10 Ω in series
Potentiometer wire of length 1 m is connected in series with 490Ω resistance and 2 V battery. If 0.2 m Vcm-I is the potential gradient, then resistance of the potentiometer wire is
  • 4.9Ω
  • 7.9Ω
  • 5.9Ω
  • 6.9Ω
A current of 0.01 mA passes through the potentiometer wire of a resistivity of 109 Ω-cm and area of cross-section 10-2cm2. The potential gradient is
  • 109 Vm-1
  • 1011 Vm-1
  • 1010 Vm-1
  • 108 Vm-1
Three moving coil galvanometers A ,B and C are made of coils of three different material having torsional constant 1,8 × 10-8 , 2.8 × 10-8 and 3.8 × 10-8 , respectively. If the three galvanometers are identical in all other respect, then in which of the above cases sensitivity is maximum ?
  • A
  • C
  • B
  • Same in each case
In a meter bridge a 30Ω resistance is connected in the left gap and a pair of resistances P and Q in the right gap. Measured from the left, the balance point is 37.5 cm, when P and Q are in series and 71.4 cm when they are parallel. The values of P and Q (in ohm) are
  • 40, 10
  • 35, 15
  • 30, 20
  • 25, 25
If resistance of voltmeter is 10000 Ω and resistance of galvanometer is 2 Ω, then find R when voltmeter reads 12V and galvanometer reads 0.1 A .
Physics-Current Electricity I-64812.png
  • 118Ω
  • 120Ω
  • 124Ω
  • 114Ω
Electrons are emitted by a hot filament and are accelerated by an electric field E as shown in fig. The two stops at the left ensure that the electron beam has a uniform cross-section.
Physics-Current Electricity I-64814.png
  • The speed of electron is more at B than at A.
  • The electric current is from left to right.
  • The current density is more at B than at A.
  • The magnitude of the current is larger at B than at A.
A metallic block has no potential difference applied across it, then the mean velocity of free electrons at absolute temperature T is
  • proportional to T
  • proportional to √T
  • zero
  • finite but independent of T.
A potential difference of V is applied at the ends of a copper wire of length l and diameter d. On doubling only d, the drift velocity.
  • becomes two times
  • becomes half
  • does not change
  • becomes one-fourth
A current through a wire depends on time as I = 10 + 4t. The charge crossing through the section of the wire in 10 seconds is
  • 50 C
  • 300 C
  • 400 C
  • 4 C
There are two concentric spheres of radius a and b respectively. If the space between them is filled with medium of resistivity ρ, then the resistance of the intergap between the two spheres will be

  • Physics-Current Electricity I-64817.png
  • 2)
    Physics-Current Electricity I-64818.png

  • Physics-Current Electricity I-64819.png

  • Physics-Current Electricity I-64820.png
A given corbon resistor has the following colour code of the various strips : Orange, red, yellow and gold. The value of resistance in ohm is

  • Physics-Current Electricity I-64822.png
  • 2)
    Physics-Current Electricity I-64823.png

  • Physics-Current Electricity I-64824.png

  • Physics-Current Electricity I-64825.png
Variation of current (I) and voltage (V) in a conductor has been shown in Fig. The resistance of the conductor is
Physics-Current Electricity I-64826.png
  • 1 Ω
  • 2 Ω
  • 3 Ω
  • 4 Ω
The Fig. shows currents in a part of an electric circuit, then current I is
Physics-Current Electricity I-64828.png
  • 1.7 A
  • 3.7 A
  • 1.3 A
  • 1 A
In the circuit Fig., the voltmeter reads 30 V. What is the resistance of the voltmeter?
Physics-Current Electricity I-64829.png
  • 1200 Ω
  • 700 Ω
  • 400 Ω
  • 300 Ω
The effective resistance between points A and B in the circuit shown in Fig. is
Physics-Current Electricity I-64831.png
  • R/3
  • R/2
  • 2 R/5
  • 3 R/5
In the circuit shown in Fig. the cells E1 and E2 have e.m. Fs. Of 4V and 8V and internal resistance 0.5Ω and 1Ω respectively. Then the p.d. across E1 and E2 will be
Physics-Current Electricity I-64833.png
  • 4.25 V ; 4.25 V
  • 3.75 V ; 3.75 V
  • 4.25 V ; 7.5 V
  • 3.75 V ; 7.5 V
A part of circuit in steady state along with the currents flowing in the branches, the values of resistance etc. is shown in fig. The current I1 and I2 are
Physics-Current Electricity I-64835.png
  • 3 A, 1 A
  • 1A, 3A
  • 2A, 1A
  • 1 A, 1A
In the circuit shown, the cell is ideal, with emf = 10 V. Each resistance is of 2Ω. The potential difference across the capacitor is
Physics-Current Electricity I-64836.png
  • 12V
  • 10V
  • 8 V
  • zero
Fig. shows a circuit with two cells in opposition to each other. One cell E1 has an emf of 6 V and internal resistance 2 Ω and other cell E2 has an e.m.f 4 V and internal resistance 8Ω.
The potential difference across the terminals A and B is
Physics-Current Electricity I-64838.png
  • 5.4 V
  • 5.6 V
  • 5.8 V
  • 6.0V
If in the circuit Fig the internal resistance of the battery is 1.5Ω and VP and VQ are potentials at P and Q respectively. What is the potential difference between the points P and Q ?
Physics-Current Electricity I-64840.png
  • zero
  • 4 volt( VP > VQ )
  • 4Volts (VQ > VP)
  • 2.5 volts (VQ > VP)
In the circuit fig., the galvanometer G shows zero deflection. If the batteries A and B have negligible internal resistance, the value of the resistor R will be
Physics-Current Electricity I-64842.png
  • 1000 Ω
  • 500 Ω
  • 100 Ω
  • 200 Ω
In the circuit shown in Fig. the total current supplied by the battery is
Physics-Current Electricity I-64844.png
  • 1 A
  • 2 A
  • 3 A
  • 6A
The wire used in the arrangement shown in fig. has a resistance r ohm per metre. The equivalent resistance between points A and B if radius of circle is 1 m is
Physics-Current Electricity I-64846.png

  • Physics-Current Electricity I-64847.png
  • 2)
    Physics-Current Electricity I-64848.png

  • Physics-Current Electricity I-64849.png

  • Physics-Current Electricity I-64850.png
In the circuit shown Fig. potential difference between X and Y will be
Physics-Current Electricity I-64852.png
  • zero
  • 20 V
  • 60 V
  • 120 V
A beam of electrons emitted from the electron gun G is accelerated by an electric field E. The area of cross- section of the beam remains constant. As the beam moves away from G
Physics-Current Electricity I-64854.png
  • the speed of the electrons increases
  • the current constituted by beam increases
  • the number of electrons per unit volume in the beam decreases
  • the number of electrons per unit volume in the beam increases.
When the current i is flowing through a conductor, the drift velocity is v. If 2i current is flowed through the same metal but having double the area of cross-section, then the drift velocity will be
  • v/4
  • v/2
  • v
  • 4v
When current flows through a conductor, then the order of drift velocity of electrons will be
  • 1010 cm/sec
  • 10–2 cm/sec
  • 104 cm/sec
  • 10–1 cm/sec
Every atom makes one free electron in copper. If 1.1 ampere current is flowing in the wire of copper having 1 mm diameter, then the drift velocity (approx.) will be (Density of copper = 9 × 103 kg m–3 and atomicweight = 63)
  • 0.3 mm/sec
  • 0.1 mm/sec
  • 0.2 mm/sec
  • 0.2 cm/sec
The current flowing through a wire depends on time as I = 3t2 + 2t + 5. The charge flowing through thecross-section of the wire in time from t = 0 to t = 2 secis
  • 22 C
  • 20 C
  • 18 C
  • 5 C
Resistance of wire at 20°C is 20 Ω and at 500°C is 60 Ω. At what temperature its resistance is 25 Ω?
  • 160° C
  • 250° C
  • 100° C
  • 80° C
The specific resistance of manganin is 50 × 10–8ohm × m. The resistance of a cube of length 50 cm will be
  • 10–6 ohm
  • 2.5 × 10–5 ohm
  • 10–8Ω
  • 5 ×10–4 ohm
A copper wire of length 1 m and radius 1 mm is joined in series with an iron wire of length 2 m and radius 3 mm and a current is passed through the wires. The ratio of the current density in the copper and iron wires is
  • 18 : 1
  • 9 : 1
  • 6 : 1
  • 2 : 3
The resistivity of iron is 1 × 10–7 ohm-m. The resistance of a iron wire of particular length and thickness is 1 ohm. If the length and the diameter of wire both are doubled, then the resistivity in ohm-m will be
  • 1 × 10–7
  • 2 × 10–7
  • 4 × 10–7
  • 8 × 10–7
When the length and area of cross-section both are doubled, then its resistance
  • Will become half
  • Will be doubled
  • Will remain the same
  • Will become four times
The resistance of a wire is 20 ohm. It is so stretched that the length becomes three times, then the newresistance of the wire will be
  • 6.67 ohm
  • 60.0 ohm
  • 120 ohm
  • 180.0 ohm
The resistivity of a wire
  • Increases with the length of the wire
  • Decreases with the area of cross-section
  • Decreases with the length and increases with the cross-section of wire
  • None of the above statement is correct
Ohm\'s law is true
  • For metallic conductors at low temperature
  • For metallic conductors at high temperature
  • For electrolytes when current passes through them
  • For diode when current flows
Drift velocity vd varies with the intensity of electricfield as per the relation

  • Physics-Current Electricity I-64863.png
  • 2)
    Physics-Current Electricity I-64864.png

  • Physics-Current Electricity I-64865.png

  • Physics-Current Electricity I-64866.png
Which of the following statement is correct?
  • Electric field is zero on the surface of currentcarrying wire
  • Electric field is non-zero on the axis of hollow current carrying wire
  • Surface integral of magnetic field for any closed surface is equal to μ0 times of total algebraic sum of current which are crossing through the closed surface.
  • None of the above
In a conductor 4 coulomb of charge flows for 2 seconds. The value of electric current will be
  • 4 volt
  • 4 ampere
  • 2 ampere
  • 2 volt
The specific resistance of a wire is ρ, its volume is 3m3 and its resistance is 3 ohm, then its length will be

  • Physics-Current Electricity I-64869.png
  • 2)
    Physics-Current Electricity I-64870.png

  • Physics-Current Electricity I-64871.png

  • Physics-Current Electricity I-64872.png
62.5 × 1018 electrons per second are flowing through awire of area of cross-section 0.1 m2, the value of current flowing will be
  • 1A
  • 0.1 A
  • 10 A
  • 0.11 A
In a closed circuit, the current I (in ampere) at an instant of time t (in second) is given by I = 4 – 0.08t. The number of electrons flowing in 50 s through thecross-section of the conductor is
  • 1.25 × 1019
  • 6.25 × 1020
  • 5.25 × 1019
  • 2.55 × 1020
A wire 100 cm long and 2.0 mm diameter has a resistance of 0.7 ohm, the electrical resistivityof the material is
  • 4.4 × 10–6 ohm × m
  • 2.2 × 10–6 ohm × m
  • 1.1 × 10–6 ohm × m
  • 0.22 × 10–6 ohm × m
A certain wire has a resistance R. The resistance of another wire identical with the first except having twice its diameter is
  • 2 R
  • 0.25 R
  • 4 R
  • 0.5 R
In hydrogen atom, the electron makes 6.6 × 1015revolutions per second around the nucleus in an orbit of radius 0.5 × 10–10 m . It is equivalent to a current nearly
  • 1 A
  • lmA
  • l μA
  • 1.6 × 10–19A
A wire of length 5 m and radius 1 mm has a resistance of 1 ohm. What length of the wire of the same material at the same temperature and of radius 2 mm will also have a resistance of 1 ohm
  • 1.25 m
  • 2.5 m
  • 10 m
  • 20 m
Consider a rectangular slab of length L and area of cross-section A. A current I is passed through it. If the length is doubled, the potential drop across the endfaces
  • Becomes half of the initial value
  • Becomes one-fourth of the initial value
  • Becomes double the initial value
  • Remains same
A wire of resistance R is elongated n-fold to make a new uniform wire. The resistance of new wire
  • nR
  • n2R
  • 2nR
  • 2 n2R
0:0:1


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