JEE Questions for Physics Current Electricity I Quiz 14 - MCQExams.com

A wire of resistor R is bent into a circular ring of radius r. Equivalent resistance between two points X and Y on its circumference, when angle XOY is ∝ , can be given by
Physics-Current Electricity I-65467.png

  • Physics-Current Electricity I-65468.png
  • 2)
    Physics-Current Electricity I-65469.png

  • Physics-Current Electricity I-65470.png

  • Physics-Current Electricity I-65471.png
Potential difference across the terminals of the battery shown in figure is (r = internal resistance of battery)
Physics-Current Electricity I-65473.png
  • 8 V
  • 10 V
  • 6 V
  • Zero
As the switch Sis closed in the circuit shown in figure, current passing through it is
Physics-Current Electricity I-65474.png
  • 4.5 A
  • 6.0 A
  • 3.0 A
  • Zero
In the following circuit a 10 m long potentiometer wire with resistance 1.2 ohm/m, a resistance R1 and an accumulator of e.m.f 2 V axe connected in series. When the e.m.f of thermocouple is 2.4 mV then the deflection in galvanometer is zero. The current supplied by the accumulator will be
Physics-Current Electricity I-65476.png
  • 4 × 10–4 A
  • 8 × 10–4 A
  • 4 × 10–3 A
  • 8 × 10–3 A
In the following circuit, bulb rated as 1.5 V, 0.45 W. If bulbs glows with full intensity then what will be the equivalent resistance between X and Y
Physics-Current Electricity I-65478.png
  • 0.45 Ω
  • 1 Ω
  • 3 Ω
  • 5 Ω
Consider the circuits shown in the figure. Both the circuits are taking same current from battery but current through R in the second circuit is 1/10 the current through R in the first circuit. If R is 11 Ω, the value of R1
Physics-Current Electricity I-65480.png
  • 9.9Ω
  • 11Ω
  • 8.8Ω
  • 7.7Ω
In order to quadruple the resistance of a uniform wire, a part of its length was uniformly stretched till the final length of the entire wire was 1.5 times the original length the part of the wire was fraction equal to
Physics-Current Electricity I-65482.png
  • 1/8
  • 1/6
  • 1/10
  • 1/4
In the circuit shown in figure reading of voltmeter is V1 when only S1 is closed, reading of voltmeter is V2 when only S2 is closed and reading of voltmeter is V3 when both S1 and S2 are closed. Then
Physics-Current Electricity I-65484.png
  • V3 > V2 > V1
  • V2 > V1 > V3
  • V3 > V1 > V2
  • V1 > V2 > V3
Current through wire XY of circuit shown is
Physics-Current Electricity I-65486.png
  • 1 A
  • 4 A
  • 2 A
  • 3 A
12 cells each having same e.m.f are connected in series with some cells wrongly connected. The arrangement is connected in series with an ammeter and two cells which are in series. Current is 3 A when cells and battery aid each other and is 2 A when cells and battery oppose each other. The number of cells wrongly connected is
  • 4
  • 1
  • 3
  • 2
Following figure shows cross-sections through three long conductors of the same length and material, with square cross-section of edge lengths as shown. Conductor B will fit snugly within conductor A, and conductor C will fit snugly within conductor B. Relationship between their end to end resistance is
Physics-Current Electricity I-65489.png
  • RA = RB = RC
  • RA> RB> RC
  • RA< RBC
  • Information is not sufficient
In the following star circuit diagram (figure), the equivalent resistance between the points A and H will be
Physics-Current Electricity I-65491.png
  • 1.944 r
  • 0.973 r
  • 0.486 r
  • 0.243 r
In the adjoining circuit diagram each resistance is of 10 Ω. The current in the arm AD will be
Physics-Current Electricity I-65493.png

  • Physics-Current Electricity I-65494.png
  • 2)
    Physics-Current Electricity I-65495.png

  • Physics-Current Electricity I-65496.png

  • Physics-Current Electricity I-65497.png
In the circuit of adjoining figure the current through 12 Ω resister will be
Physics-Current Electricity I-65499.png
  • 1A
  • 2)
    Physics-Current Electricity I-65500.png

  • Physics-Current Electricity I-65501.png

  • Physics-Current Electricity I-65502.png
The reading of the ideal voltmeter in the adjoining diagram will be
Physics-Current Electricity I-65504.png
  • 4 V
  • 8 V
  • 12 V
  • 14 V
The resistance of the series combination of two resistances is S. When they are joined in parallel the total resistance is P. If S = nP, then the minimum possible value of n is
  • 4
  • 3
  • 2
  • 1
A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10 divisions per milliampere and voltage sensitivity is 2 divisions per millivolt. In order that each division reads 1 volt, the resistance in ohms needed to be connected in series with the coil will be
  • 99995
  • 9995
  • 103
  • 105
If n, e, τ and m respectively represent the density, charge relaxation time and mass of the electron, then the resistance of a wire of length l and area of cross-section A will be

  • Physics-Current Electricity I-65686.png
  • 2)
    Physics-Current Electricity I-65687.png

  • Physics-Current Electricity I-65688.png

  • Physics-Current Electricity I-65689.png
Consider a thin square sheet of side L and thickness t, made of a material of resistivity ρ. The resistance between two opposite faces, shown by the shaded areas in the figure is
Physics-Current Electricity I-65508.png
  • Directly proportional to L
  • Directly proportional to t
  • Independent of L
  • Independent of t
In the adjacent shown circuit, a voltmeter of internal resistance R, when connected across B and C reads 100/3V. Neglecting the internal resistance of the battery, the value of R is
Physics-Current Electricity I-65510.png
  • 100 KΩ
  • 75 KΩ
  • 50 KΩ
  • 25 KΩ
To verify ohm\'s law, a student is provided with a test resistor RT, a high resistance R1, a small resistance R2, two identical galvanometers G1 and G2, and a variable voltage source V. The correct circuit to carry out the experiment is

  • Physics-Current Electricity I-65512.png
  • 2)
    Physics-Current Electricity I-65513.png

  • Physics-Current Electricity I-65514.png

  • Physics-Current Electricity I-65515.png
Two conductors have the same resistance at 0°C but their temperature coefficients of resistance are α1 and α2. The respective temperature coefficients of their series and parallel combinations are nearly

  • Physics-Current Electricity I-65516.png
  • 2)
    Physics-Current Electricity I-65517.png

  • Physics-Current Electricity I-65518.png

  • Physics-Current Electricity I-65519.png
Variation of current passing through a conductor as the voltage applied across its ends is varied as shown in the adjoining diagram. If the resistance (R) is determined at the points A, B, C and D, we will find that
Physics-Current Electricity I-65521.png
  • RC = RD
  • RB > RA
  • RC > RB
  • None of these
The voltage V and current I graph for a conductor at two different temperatures T1 and T2 are shown in the figure. The relation between T1 and T2 is
Physics-Current Electricity I-65523.png
  • T1>T2
  • T1 ≈ T2
  • T1 = T2
  • T1< T2
From the graph between current I and voltage V shown below, identify the portion corresponding to negative resistance
Physics-Current Electricity I-65525.png
  • AB
  • BC
  • CD
  • DE
I–V characteristic of a copper wire of length L and area of cross-section A is shown in figure. The slope of the curve becomes
Physics-Current Electricity I-65526.png
  • More if the experiment is performed at higher temperature
  • More if a wire of steel of same dimension is used
  • More if the length of the wire is increased
  • Less if the length of the wire is increased
E denotes electric field in a uniform conductor, I corresponding current through it, vd drift velocity of electrons and P denotes thermal power produced in the conductor, then which of the following graph is incorrect?

  • Physics-Current Electricity I-65528.png
  • 2)
    Physics-Current Electricity I-65529.png

  • Physics-Current Electricity I-65530.png

  • Physics-Current Electricity I-65531.png
The two ends of a uniform conductor are joined to a cell of e.m.f. E and some internal resistance. Starting from the midpoint P of the conductor, we move in the direction of current and return to P. The potential Vat every point on the path is plotted against the distance covered (x). Which of the following graphs best represents the resulting curve?

  • Physics-Current Electricity I-65533.png
  • 2)
    Physics-Current Electricity I-65534.png

  • Physics-Current Electricity I-65535.png

  • Physics-Current Electricity I-65536.png
The resistance R1 of a conductor varies with temperature t as shown in the figure. If the variation is represented by R1 = R0 [1 = αt + βt2]
Physics-Current Electricity I-65537.png
  • α and β are both negative
  • α and β are both positive
  • α is positive and β is negative
  • α is negative and β is positive
Variation of current and voltage in a conductor has been shown in the diagram below. The resistance of the conductor is.
Physics-Current Electricity I-65539.png
  • 4 Ω
  • 2 Ω
  • 3 Ω
  • 1 Ω
Resistance as shown in figure is negative at
Physics-Current Electricity I-65541.png
  • A
  • B
  • C
  • None of these
For a cell, the graph between the potential difference (V) across the terminals of the cell and the current (I) drawn from the cell is shown in the figure. The e.m.f. and the internal resistance of the cell are
Physics-Current Electricity I-65542.png
  • 2V, 0.5 Ω
  • 2V, 0.4 Ω
  • > 2V, 0.5 Ω
  • > 2V, 0.4 Ω
When a current I is passed through a wire of constant resistance, it produces a potential difference V across its ends. The graph drawn between log I and log V will be

  • Physics-Current Electricity I-65544.png
  • 2)
    Physics-Current Electricity I-65545.png

  • Physics-Current Electricity I-65546.png

  • Physics-Current Electricity I-65547.png
The V–i graph for a conductor at temperatures T1 and T2are as shown in the figure. (T2– T1) is proportional to
Physics-Current Electricity I-65549.png
  • cos 2θ
  • sin 2θ
  • cot 2θ
  • tan 2θ
A cylindrical conductor has uniform cross–section. Resistivity of its material increases linearly from left end to right end. If a constant current is flowing through it and at a section distance x from left end, magnitude of electric field intensity is E, which of the following graphs is correct?

  • Physics-Current Electricity I-65551.png
  • 2)
    Physics-Current Electricity I-65552.png

  • Physics-Current Electricity I-65553.png

  • Physics-Current Electricity I-65554.png
The V–i graph for a conductor makes an angle θ with V–axis. Here V denotes the voltage and i denotes current. The resistance of conductor is given by
  • sin θ
  • cos θ
  • tan θ
  • cot θ
A battery consists of a variable number \'n\' of identical cells having internal resistances connected in series. The terminals of battery are short circuited and the current i is measured. Which of the graph below shows the relationship between i and n

  • Physics-Current Electricity I-65557.png
  • 2)
    Physics-Current Electricity I-65558.png

  • Physics-Current Electricity I-65559.png

  • Physics-Current Electricity I-65560.png
In an experiment, a graph was plotted of the potential difference V between the terminals of a cell against the circuit current i by varying load rheostat. Internal conductance of the cell is given by
Physics-Current Electricity I-65562.png

  • Physics-Current Electricity I-65563.png
  • 2)
    Physics-Current Electricity I-65564.png

  • Physics-Current Electricity I-65565.png

  • Physics-Current Electricity I-65566.png
V–i graphs for parallel and series combination of two identical resistors are as shown in figure. Which graph represents parallel combination?
Physics-Current Electricity I-65568.png
  • A
  • B
  • A and B both
  • Neither A nor B
The relaxation time in conductors
  • Increases with the increase of temperature
  • Decreases with the increase of temperature
  • It does not depend on temperature
  • All of sudden changes at 400 K
The ammeter has range 1 ampere without shunt. The range can be varied by using different shunt resistances. The graph between shunt resistance and range will have the nature
Physics-Current Electricity I-65570.png
  • P
  • Q
  • R
  • S
For the circuit shown in the figure
Physics-Current Electricity I-65571.png
  • The current I through the battery is 7.5 mA
  • The potential difference across RL is 18 V
  • Ratio of powers dissipated in R1 and R2is 3
  • If R1 and R2are interchanged, magnitude of the power dissipated in RL will decrease by a factor of 9
A microammeter has a resistance of 100 Ω and a full scale range of 50 μA. It can be used as a voltmeter or as a higher range ammeter provided a resistance is added to it. Pick the correct range and resistance combination (s)
  • 50 V range with 10 kΩ resistance in series
  • 10 V range with 200 kΩ resistance in series
  • 5 mA range with 1 Ω resistance in parallel
  • 10 mA range with 1 Ω resistance in parallel
For the resistance network shown in the figure, choose the correct option (s)
Physics-Current Electricity I-65574.png
  • The current through PQ is zero
  • I1 = 3A
  • The potential at S is less than that at Q
  • I2 = 2A
Statement I In a Meter Bridge experiment, null point for an unknown resistance is measured. Now, the unknown resistance is put inside an enclosure maintained at a higher temperature. The null point can be obtained at the same point as before by decreasing the value of the standard resistance.
Statement II Resistance of a metal increases with increase in temperature.
  • Statement I is true, statement II is true ; statement II is a correct explanation for statement I
  • Statement I is true, statement II is true ; statement II is not a correct explanation for statement I
  • Statement I is true, statement II is false
  • Statement I is false, statement II is true
Statement I The temperature dependence of resistance is usually given as R = R0 (1 + α∆t). The resistance of a wire changes from 100 Ω to 150Ω when its temperature is increased from 27°C to 227°C. This implies that α = 2.5 × 10–3/° C
Statement II R = R0 (1 + α∆t) is valid only when the change in the temperature ∆T is small and ∆R = (R – R0) << R0.
  • Statement I is true, statement II is true ; statement II is a correct explanation for statement I
  • Statement I is true, statement II is true ; statement II is not a correct explanation for statement I
  • Statement I is true, statement II is false
  • Statement I is false, statement II is true
Consider a block of conducting material of resistivity ‘ρ’ shown in the figure. Current T enters at ‘A’ and leaves from ‘D’. We apply superposition principle to find voltage ‘∆V’ developed between \'B\' and \'C\' The calculation is done in the following steps :
(i) Take current ‘I’ entering from ‘A’ and assume it to spread over a hemispherical surface in the block.
(ii) Calculate field E (r) at distance V from A by using Ohm\'s law E = ρj, where; is the current per unit area at `r\'.
(iii) From the `r\' dependence of E (r), obtain the potential V (r) at r.
(iv) Repeat (i), (ii) and (iii) for current ‘I’ leaving ‘D’ and superpose results for ‘A’ and ‘D’.
For current entering at A, the electric field at a distance ‘r’ from A is
Physics-Current Electricity I-65576.png

  • Physics-Current Electricity I-65577.png
  • 2)
    Physics-Current Electricity I-65578.png

  • Physics-Current Electricity I-65579.png

  • Physics-Current Electricity I-65580.png
Consider a block of conducting material of resistivity ‘ρ’ shown in the figure. Current T enters at ‘A’ and leaves from ‘D’. We apply superposition principle to find voltage ‘∆V’ developed between \'B\' and \'C\' The calculation is done in the following steps :
(i) Take current ‘I’ entering from ‘A’ and assume it to spread over a hemispherical surface in the block.
(ii) Calculate field E (r) at distance V from A by using Ohm\'s law E = ρj, where; is the current per unit area at `r\'.
(iii) From the `r\' dependence of E (r), obtain the potential V (r) at r.
(iv) Repeat (i), (ii) and (iii) for current ‘I’ leaving ‘D’ and superpose results for ‘A’ and ‘D’.
Physics-Current Electricity I-65582.png

  • Physics-Current Electricity I-65583.png
  • 2)
    Physics-Current Electricity I-65584.png

  • Physics-Current Electricity I-65585.png

  • Physics-Current Electricity I-65586.png
Electrical resistance of certain materials, known as superconductors, changes abruptly from a nonzero value to zero as their temperature is lowered below a critical temperature TC(0).
An interesting property of superconductors is that their critical temperature becomes smaller than TC (if they are placed in a magnetic field, i.e., the critical temperature TC(B) is a function of the magnetic field strength B. The dependence of TC (B) on B is shown in the figure
In the graphs below, the resistance R of a superconductor is shown as a function of its temperature T for two different magnetic fields B1 (solid line) and B2 (dashed line). If B2 is larger than B1, which of the following graphs shows the correct variation of R with T in these fields
Physics-Current Electricity I-65587.png

  • Physics-Current Electricity I-65588.png
  • 2)
    Physics-Current Electricity I-65589.png

  • Physics-Current Electricity I-65590.png

  • Physics-Current Electricity I-65591.png
Electrical resistance of certain materials, known as superconductors, changes abruptly from a nonzero value to zero as their temperature is lowered below a critical temperature TC(0).
An interesting property of superconductors is that their critical temperature becomes smaller than TC (if they are placed in a magnetic field, i.e., the critical temperature TC(B) is a function of the magnetic field strength B. The dependence of TC (B) on B is shown in the figure
A superconductor has TC(= 100 K. When a magnetic field of 7.5 Tesla is applied, its TC decreases to 75 K. For this material one can definitely say that when
Physics-Current Electricity I-65592.png
  • B = 5 Tesla, TC (B) = 80 K
  • B = 5 Tesla, 75 K C (B)<100 K
  • B =10 Tesla, 75 K C (B)<100 K
  • B =10 Tesla, TC (B) = 70 K
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