Q.1
Two resistance's R1 and R2 are made of different materials. The temperature coefficient of the material of R1 is α and of the material of R2 is -β. The resistance of the series combination of R1 and R2 will not change with temperature, if R1 / R2 equals [ MPPMT 1997]
  • a) α / β
  • b) ( α+ β) /( α- β)
  • c)( α2 + β2 ) / αβ
  • d)β / α
Q.2
Drift velocity is equal to [ BHU 1995]
  • a) 1 / ne
  • b) I / neA
  • c)I/ne
  • d)i/A
Q.3
If n, e, τ and m represent electron density, charge, relaxation time and mass of an electron respectively, then the resistance of a wire of length l and cross-sectional area A is
  • a)
    ch-14_qn-124choice_img_no1.png
  • b)
    ch-14_qn-124choice_img_no2.png
  • c)
    ch-14_qn-124choice_img_no3.png
  • d)
    ch-14_qn-124choice_img_no4.png
Q.4
A copper wire and aluminum wire of same length have same resistance. Specific resistance of aluminum is more than that of copper. Which of the following statement is correct?
  • a)Mass of copper and aluminum wire same
  • b) Mass of copper wire is more than that of aluminum wire
  • c)MAss of copper wire is less than that of aluminum wire
  • d)Nothing can be said as information given is incomplete
Q.5
Constanton wire is used for making standard resistance because it has [ MPPMT 1999]
  • a) low specific resistance
  • b) high specific resistance
  • c)negligible temperature coefficient of resistance
  • d)high melting point
Q.6
An α particle ( mass=4mp, charge 2e) is revolving in a circular orbit of radius 1Å, with speed 3.14×106m/s. The equivalent current is
  • a) 1.6 mA
  • b) 3.2mA
  • c)6.4 mA
  • d)0.8mA
Q.7
The resistance of certain piece of wire is 9Ω, the resistance of second piece, identical to first, except that its diameter is 3 times as large will be [ BIT 1989]
  • a) 1 Ω
  • b) 3Ω
  • c) 9Ω
  • d) 27Ω
Q.8
Two wires of same material have lengths L and 2L and cross-sectional area 4A and A respectively. The ratio of their specific resistance's would be [ CPMT 1993]
  • a)1 : 1
  • b) 1 : 8
  • c)8 : 1
  • d)1 : 2
Q.9
Two wires of same length and material have their cross-sections in the ratio of 1:3 The two wires are joined so that their ends fuse into one another without any other change. The ratio of the resistance of the fused wire and the wire of small cross-section is
  • a) 1:3
  • b) 1:4
  • c)1:2
  • d)4:1
Q.10
A resistor is in the shape of truncated right circular cone. The end radii are r1 and r2 ( r1 < r2) and altitude is l. If the taper is small, then the resistance between the plane faces of this resistor is
  • a)
    ch-14_qn-131choice_img_no1.png
  • b)
    ch-14_qn-131choice_img_no2.png
  • c)
    ch-14_qn-131choice_img_no3.png
  • d)
    ch-14_qn-131choice_img_no4.png
Q.11
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 is determined at the point A, B, C and D. We find that resistance at [CPMT 1989]
ch-14_que_no-132_img_no1.png
  • a) C and D are equal
  • b) B is higher than at A
  • c) C is higher than at B
  • d) A is lower than at B
Q.12
A steady beam of α- particles ( q=2e) traveling with constant kinetic energy of 20MeV carries a current 0.25µA. If the beam is directed perpendicular to a plane surface, how many α- particles strike the surface in 3 secs?
  • a)2.3×1012
  • b) 2.3×1019
  • c)2.3×108
  • d)2.3×106
Q.13
An electric cable of copper has just one wire of radius 9mm. Its resistance is 5Ω. This single copper wire of the cable is replaced by 6 different well insulated copper wires each of radius 3mm. The total resistance of the cable will now be equal to [ CPMT 1989]
  • a) 7.5Ω
  • b) 45Ω
  • c)90Ω
  • d)270Ω
Q.14
Two conductors are made of the same material and have the same length. Conductor A is solid wire of diameter 1mm. Conductor B is hollow tube of outer diameter 2mm and inner diameter 1mm. The ratio of resistance RA to RB is :
  • a) 3:1
  • b) 1:3
  • c)1:1
  • d)2:1
Q.15
The temperature of a metal wire rises when an electric current passes through it because
  • a) collision of conduction electrons with each other releases heat energy
  • b) collision of conduction electrons with the atoms of the metal gives them energy which appears as heat
  • c) When the conduction electrons fall from higher energy level to lower energy level heat energy is released
  • d) Heat energy is released when the conduction electrons are separated from their parent atoms
Q.16
The current I and voltage V graph for a given metallic wire at to different temperatures T1 and T2 are shown in the figure. It is concluded that
ch-14_que_no-137_img_no1.png
  • a) T1 > T2
  • b) T1 < T2
  • d) T1 = 2T2
  • c) T₁ = T₂
Q.17
A copper wire of length l and radius r is nickel plated till its final radius is R and length l. If the specific resistance of nickel and copper ne Kn and Kc then the conductance of nickeled wire is
ch-14_que_no-138_img_no1.png
  • a)
    ch-14_qn-138choice_img_no1.png
  • b)
    ch-14_qn-138choice_img_no2.png
  • c)
    ch-14_qn-138choice_img_no3.png
  • d)
    ch-14_qn-138choice_img_no4.png
Q.18
A steady current i passes through a linear conductor of uniform cross-section. Any given segment of the conductor has
  • a) a net negative charge
  • b) a net positive charge
  • c)a zero net charge of any kind
  • d)a net charge proportional to the volume of the segment
Q.19
The V-I graph for conductor at temperatures Ti and T2 are shown in the figure. (T2 - T1) is proportional to :
ch-14_que_no-140_img_no1.png
  • a) cos2θ
  • b) sin2θ
  • c) cot2θ
  • d) tan2θ
Q.20
The resistivity of a material is inversely proportional to
  • a)number density of electrons as well as relaxation time
  • b) number density of electrons and directly proportional ro relaxation time
  • c)relaxation time and directly proportional to the number density of electrons
  • d)neither relaxation time nor number density of electrons
Q.21
A steady current is passing through a linear conductor of non-uniform cross-section. The net quantity of charge crossing any cross-section per second is
  • a) directly proportional to the area of cross-section
  • b) inversely proportional to the area of cross-section
  • c)independent of the area of cross-section
  • d)directly proportional to the length of conductor
Q.22
The resistance of carbon filament at 0°C is 104 Ω. It is connected in series to an iron wire. The temperature coefficient of resistivity of carbon and iron are -0.0003 and +0.0052/ °C respectively. What must be the resistance of iron wire so that the combined resistance does not change with temperature?
  • a) 15Ω
  • b) 6Ω
  • c)1.5Ω
  • d)156/104 Ω
Q.23
A copper wire of length 1 metre and radius 1mm is joined in series with an iron wire of length two metres and radius 3mm and current is passed through the wire. the ratio of the current density in the copper and iron wire is [ MPPMT 1994]
  • a) 18/1
  • b) 9/1
  • c) 6/1
  • d) 2/3
Q.24
A ring of radius R and linear charge density λ on its surface is performing rotational motion about an axis perpendicular to its plane. If the angular velocity of the ring is ω, how much current is constituted by the ring [ GSEB]
  • a)Rωλ
  • b) R2ωλ
  • c)Rω2λ
  • d)Rωλ2
Q.25
A cell supplies a current of 0.9A through a 2Ω resistance and current of 0.3A through a 7Ω resistor. What is the internal resistance of the cell?
  • a) 1.5Ω
  • b) 1.0Ω
  • c)1.2Ω
  • d)2.0Ω
Q.26
The cross sectional area of the plane shown in figure is equal to 1cm2A current flows through a conductor. The current density at point P in the conductor will be ..
ch-14_que_no-147_img_no1.png
  • a)
    ch-14_qn-147choice_img_no1.png
  • b)
    ch-14_qn-147choice_img_no2.png
  • c)
    ch-14_qn-147choice_img_no3.png
  • d)
    ch-14_qn-147choice_img_no4.png
Q.27
A resistive wire is stretched till its length is increased by 100%. Due to the consequent decrease in a diameter, the change in the resistance of a stretched wire will be ... [ GSEB]
  • a)300%
  • b) 200%
  • c)100%
  • d)50%
Q.28
P and Q are to points on a uniform ring of resistance R. O is the centre of the ring. If the part PQ of the ring subtends an angle θ at the centre O of the ring ( i.e. ∠POQ=θ), the equivalent resistance of the ring between the points P and Q will be .... [ Radius of ring=r and resistance per unit length of the ring=ρ] [GSEB]
  • a)
    ch-14_qn-151choice_img_no1.png
  • b)
    ch-14_qn-151choice_img_no2.png
  • c)
    ch-14_qn-151choice_img_no3.png
  • d)
    ch-14_qn-151choice_img_no4.png
Q.29
Figure shows a part of a closed circuit. If the current flowing through it is 2A, what will be the potential difference between point A and B
ch-14_que_no-152_img_no1.png
  • a) +2V
  • b) +1V
  • c) -2V
  • d) -1V
Q.30
A voltmeter of resistance R is used to measure the potential difference across a resistance r. In which case the reading will be nearest to that in the absence of voltmeter
  • a) R < r
  • b) R > r
  • c)R=r
  • d)R=0
0 h : 0 m : 1 s