Electricity & Magnetism-I - Quanta: BS/MSc Physics Books

1: Two point charges are placed at some distance and force between them is F. If distance between two point charges is doubled, then electrostatic force between them is

a. F

b. F/2

c. 2F

d. F/4

2: A charged particle is placed in an electric field. The force on particle when its charge is doubled is

a. F

b. 2F

c. F/2

d. F/4

3: Electric flux through a surface depends upon

a. Area of surface

b. Orientation of area

c. Magnitude of electric field intensity

d. All of these

4: Two point charges at a certain distance r in air exert a force F on each other. The distance at which these charges will experience same force in a medium of relative permeability is

a. $r^\prime=r\epsilon_r$

b. $r^\prime=r{/\epsilon}_r$

c. $\mathbf{r}^\prime=\mathbf{r}/\sqrt{\mathbf{\epsilon}_\mathbf{r}}$

d. None of these

5: Two point charges repel each other with a force of 12N. If a charge of is given to each of these, then new force is

a. Zero

b. 4N repulsive

c. 4N attractive

d. 12N attractive

6: The magnitude of electric field such that an electron placed in it would experience an electric force equal to its weight is

a. mge

b. mg/e

c. $\mathbf{e}/\mathbf{mg}$

d. None of these

7: A charge q is placed at centre of a cube, then electric flux through one face is

a. $q/\epsilon_0$

b. $q/4\epsilon_0$

c. $\mathbf{q}/{\mathbf{6\epsilon}}_\mathbf{0}$

d. $q/{8\epsilon}_0$

8: Two point charges q and –q situated at a distance d have force F. I f one charge is constant while other moves round the former in a circle of radius r, then work done is

a. $F\ \times r$

b. $F\times2\pi r$

c. $F/2\pi r$

d. Zero

9: A particle of mass m and charge q is thrown with a uniform speed v against an electric field E. The distance it will travel before coming to momentary rest is

a. $\mathbf{m}\mathbf{v}^\mathbf{2}/\mathbf{2qE}$

b. $mv^2/qE$

c. $mv^2/4qE$

d. None of these

10: A uniform electric field of 1N/C is set up by a uniform distribution of charge in the xy-plane. The electric field inside a metal ball placed 0.5m above the xy-plane is

a. $mv^2/4qE$

b. Zero

c. 0.25N/C

d. None of these

11: If the distance between two charged objects is halved, then force between them becomes

a. Four times

b. Doubled

c. One half

d. None of these

12: A suspended object A is attracted to a neutral wall. It is also attracted to a positively charged object B. Which of the following is true about object A?

a. It has a negative charge

b. It is uncharged

c. It may be either charged or uncharged

d. It has a positive charge.

13: In which of the following contexts can Gauss’s law not be readily applied to find the electric field?

a. Near a long uniformly charged wire

b. Inside a uniformly charged ball

c. Outside a uniformly charged sphere

d. All of these

14: A circular ring of charge of radius r has a total charge q uniformly distributed around it. The magnitude to the electric field at the centre of the ring is

a. $\frac{1}{4\pi\epsilon_0}\frac{q}{r^2}$

b. $\frac{1}{4\pi\epsilon_0}\frac{q^2}{r^2}$

c. Zero

d. None of these

15: The direction of field lines around a negative charge q is

a. Readily outward

b. Readily inward

c. Circular

d. None of these

16: Electric flux through a closed surface depends upon

a. Shape of surface

b. Size of surface

c. Medium

d. Medium and charged enclosed

17: Magnitude of the flux of a constant electric field of in the x-direction through a rectangle with area in the yz-plane is

a. $3\times{10}^6\frac{V}{m}$

b. $\mathbf{10Nm^2/C}$

c. Zero

d. None of these

18: In Millikan experiment, the oil drop can be suspended between two plates when gravitational force is equal to

a. Electric force

b. Magnetic force

c. Atomic force of oil used

d. All of these

19: When 10²⁰ electrons are removed from a neutral metal sphere then charge on sphere becomes

a. $\mathbf{16\mu C}$

b. $-16\mu C$

c. $32\mu C$

d. None of these

21: If value of ampere is reduced to half its present value, then value of as compared to its previous value will change

a. Four times

b. One fourth

c. Two times

d. None of above

22: The potential at a point V(r) due to two charges located at positions is

a. $\frac{1}{4\pi\epsilon_0}(\frac{q_1}{r_1}+\frac{q_2}{r_2})$

b. $\frac{\mathbf{1}}{\mathbf{4\pi}\mathbf{\epsilon}<em>\mathbf{0}}(\frac{\mathbf{q}</em>\mathbf{1}}{|\mathbf{r}-\mathbf{r}<em>\mathbf{1}|}+\frac{\mathbf{q}</em>\mathbf{2}}{|\mathbf{r}-\mathbf{r}_\mathbf{2}|})$

c. Both a & b

d. None of these

23: A charged particle of mass m and charge q is released in an electric field of magnitude E. Its kinetic energy after time t is

a. $2E^2t^2/mq$

b. $\mathbf{q^2E^2t^2/2m}$

c. $E^2t^2/2m$

d. None of these.

24: If a charged spherical conductor of radius 10 cm has potential V at a point distant 5cm from its centre, then the potential at a point distant 15cm from centre will be

a. 3V

b. 3/2V

c. 2/3V

d. None of above.

25: The electric field in a region is directed outwards and is proportional to distance r from origin. Taking electric potential at origin to be zero it is proportional to

a. R

b. r²

c. 1/r

d. Insufficient data to reply.

26: A circular ring of radius r carries a charge q uniformly distributed on it. A small length dl is cut off. The electric field at centre due to remaining wire is

a. $\frac{q}{4\pi\epsilon_0r}$

b. $\frac{q}{4\pi\epsilon_0r^2}$

c. $\frac{qdl}{4\pi\epsilon_0r^3}$

d. $\mathbf{\frac{qdl}{8\pi^2\epsilon_0r^3}}$

27: A uniform electric field pointing in x-direction exists in a region. Let A be origin, B a point at x=1cm and C, at y=1cm, then potential at points A, B and C satisfy

a. V_A> V_B

b. V_A< V_B

c. V_A> V_C

d. None of above.

28: A charge q is placed at the centre of shell of radius r and another charge is placed on the shell. The potential at x = r/2 is

a. $\frac{1}{4\pi\epsilon_0}\frac{q}{r}$

b. $\frac{1}{4\pi\epsilon_0}\frac{q+q^\prime}{r}$

c. $\frac{1}{4\pi\epsilon_0}\frac{qq^\prime}{r}$

d. $\mathbf{\frac{1}{4\pi\epsilon_0}(\frac{2q}{r}+\frac{q^\prime}{r})}$

29: Two equal point charges are at on x-axis. Another point charge q is placed at the origin. The change in electrical potential energy of when it is displaced at a small distance r along the x-axis is approximately proportional to

a. 1/r

b. r

c. r²

d. None of these.

30: Two copper spheres of same radii one hollow and other solid are charged to same potential, then

a. Both will hold same charge

b. Solid will have more charge

c. Hollow will have more charge

d. Insufficient data to reply

31: Charge q each are placed at (0, a,0) & (0, -a,0) and a charge –q is placed at (5a,0,0), then motion is

a. Linear

b. Circular

c. Simple harmonic

d. Oscillatory but not SHM

32: The potential at a point is being constant. Electric field vector is

a. $\mathbf{2\hat{i}+4y\hat{j}+2az\hat{k}}$

b. $2x\hat{i}+4\hat{j}+2az\hat{k}$

c. $2x\hat{i}+4y^2\hat{j}+az^2\hat{k}$

d. More information is needed

33: The potential on surface of a charged metallic sphere of radius 5cm is 10V. The potential at centre of sphere will be

a. 10V

b. 20 V

c. 17V

d. Zero

34: The work done on a unit positive charge in bringing it from infinity to any point is called

a. Electric intensity at that point

b. Electric potential at that point

c. Potential difference

d. Kinetic energy/work done

35: The potential difference between two points can be written as

a. $\mathbf{\Delta V=-\frac{1}{4\pi\epsilon_0}\int\frac{q}{r^2}dr}$

b. $\Delta V=-\frac{1}{4\pi\epsilon_0}\int\frac{q}{r}dr$

c. $\Delta V=\frac{1}{4\pi\epsilon_0}\int\frac{q}{r^2}dr$

d. None of these.

36: The dimensions of potential are same as that of

a. Force per unit charge

b. Electric field per unit charge

c. Work done per unit charge

d. All of these

37: A charge of 1µC is moved in a circle of radius $\left(\frac{20}{\pi}\right)$ m about another charge of 10µC at centre. The work done is so doing is

a. Infinite

b. $4\times{10}^{-9}J$

c. $1.6\times{10}^{-19}J$

d. Zero.

38: A point charge q located at origin. The amount of work done in bringing a unit positive charge from infinity to origin is

a. Infinite

b. Zero

c. $4\times{10}^{-9}J$

d. None

39: Net force on a dipole in a uniform electric field is

a. $F=qE$

b. F=-qE

c. Zero

d. Unknown

40: Electric field at any point due to dipole is, $\mathbf{\vec{E}=\frac{1}{4\pi\epsilon_0}{\frac{3(\vec{p}.\vec{r})\vec{r}}{r^5}-\frac{\vec{p}}{r^3}}}$ Electric field on a line normal to axis of dipole is

a. $\mathbf{\vec{E}=-\frac{1}{4\pi\epsilon_0}\frac{\vec{p}}{r^2}}$

b. $\vec{E}=-\frac{1}{4\pi\epsilon_0}\frac{\vec{p}}{r^3}$

c. $\vec{E}=\frac{1}{4\pi\epsilon_0}\frac{\vec{p}}{r^4}$

d. None of these.

41: A parallel plate capacitor of capacitance C is charged using a battery of . After capacitor is charged, the battery is removed and distance between capacitors is double, then the energy stored is

a. $CV_0^2/2$

b. $CV_0^2/4$

c. $\mathbf{CV_0^2}$

d. None of these

42: Three capacitors of each are to be connected in such a way that the net capacitance is . Then

a. All capacitors are in series

b. All capacitors are in parallel

c. Two are in series and one in parallel

d. None of these

43: Three capacitors of each are to be connected in series. The equivalent capacitance will be

a. 6F

b. 2F/3

c. 5F

d. 3F/2

44: If diameter of Earth is 12800km, then its capacitance will be

a. 711µF

b. 111µF

c. 211µF

d. 331µF

45: The electric energy density between plates of charged capacitor is

a. $\frac{q}{2\epsilon_0A}$

b. $\mathbf{\frac{q^2}{2\epsilon_0A^2}}$

c. CV/2

d. $\frac{q}{2\epsilon_0A^2}$

46: When dielectric medium of constant is filled between the plates of a charged parallel plate capacitor, then energy stored becomes, as compared to previous value

a. $k_e^2$ times

b. $k_e^{-2}$ times

c. $\mathbf{k_e^{-1}}$ times

d. $k_e$ times

47: The capacitance of a parallel plate capacitor is . If a dielectric material of dielectric constant 16 is placed between the plates, then new capacitance is

a. $64\mu F$

b. $40\mu F$

c. $0.25\mu F$

d. $1/64\mu F$

48: A parallel plate capacitor has capacitance C. The separation between plates is doubled and a dielectric medium is introduced between the plates. If capacity now becomes 2C, dielectric constant of medium is

a. 8

b. 4

c. 2

d. 1

49: If we increase distance between two plates of capacitor, then capacitance will

a. Increase

b. Decrease

c. Remains same

d. None of these

50: A parallel plate capacitor is first charged and then dielectric slab is introduced between plates. The quality that remains unchanged is

a. Potential V

b. Capacitance C

c. Energy E

d. Charge q

51: Which material sheet should be placed between plates of parallel capacitor in order to increase its capacitance?

a. Copper

b. Mica

c. Tin

d. Iron

52: Farad is not equivalent to

a. $J/V^2$

b. $Q^2/J$

c. Q/V

d. $\mathbf{CV^2}$

53: There is an air filled parallel plate capacitor. When plate separation is doubled and the space is filled with wax, the capacitance increases to . The dielectric constant of wax is

a. 8

b. 6

c. 2

d. 4

54: Two metallic spheres of capacitances respectively carry some charges. They are brought in contact and then separated. The final charges on them will satisfy the relation

a. $q_1C_1{=q}_2C_2$

b. $q_1=q_2\neq0$

c. $\mathbf{q_1C_2{=q}_2C_1}$

d. $q_1=0=q_2$

55: A charge q is placed at mid-point of line joining two equal charges Q. The system of three charges will be in equilibrium when q has value

a. Q/2

b. -Q/2

c. Q/4

d. -Q/4

56: Net charge on capacitor is

a. Infinity

b. q/2

c. 2q

d. Zero

57: A 100µF capacitor is charged to 200V. It is discharged through resistance. The amount of heat generated will be

a. 0.4J

b. 4J

c. 0.2J

d. 2J

58: The capacitance of parallel plate capacitor in air is . If dielectric medium is placed then potential difference reduces to 1/6 of original value. The dielectric constant of material is

b. 3

c. 4.4

d. 2.2

59: A cylindrical capacitor has radii The amount of energy stored in a cylinder of radius is …………. of total energy

a. Half

b. One-third

c. Same as

d. None of above

60: A thin material plate is used in between a parallel plate capacitor having capacitance C, then new capacitance C’ is

a. Greater than C

b. Less than C

c. Same as C

d. Can’t be changed

61: A given battery is rated as 250ampere-hours. This rating indicates which of the following quantities that can be drawn from battery

a. Energy

b. Power

c. Charge

d. Voltage

62: A conducting wire is quadrupled in length and tripled in diameter, then its resistance

a. Increases

b. Decreases

c. Remains same

d. None of these

63: If wire of resistance R is stretched to double its length, its resistance becomes

a. 4R

b. R/4

c. R/2

d. None of these

64: A wire carries current $i=4+2t^2$ is in amperes, then number of coulombs which passes through between is

a. 127.4C

b. 164C

c. 484.3C

d. 603.3C

65: Two wires of same material having lengths L and 2L and cross-sectional area 4A and A respectively. The ratio of their specific resistances would be

a. 2:1

b. 1:2

c. 1:1

d. None of above

66: The resistance of a conductor at absolute zero (0K) is

a. Zero

b. Infinite

c. Positive

d. Can’t be predict

67: A steady current flows in a metallic conductor of non-uniform cross-section. The quantity/quantities constant along length of conductor is/are

a. Current, electric field and drift velocity

b. Current and drift speed

c. Current

d. Drift speed

68: The resistance of a wire is R. It is cut into four equal parts and bounded together in parallel. The equivalent resistance will be

a. R

b. R/16

c. 4R

d. R/4

69: Two wires of same materials have same length but their areas are in ratio 3:1. The two wires are connected in series. The resistance of thicker wire is . Total resistance of combination is

a. 40/3Ω

b. 20Ω

c. 40Ω

d. 30Ω

70: A copper wire is connected across a battery. The drift velocity of electron is . If another wire of same length and double the radius is connected across same battery, then drift velocity will be

a. $\mathbf{v_d}$

b. 4 $v_d$

c. 2 $v_d$

d. $v_d/2$

71: If resistivity of potentiometer wire be and of cross-section be A. If is current through potentiometer wire, then potential gradient along wire will be

a. $\frac{\rho L}{A}$

b. $\frac{L}{\rho A}$

c. $\mathbf{\frac{\rho i}{A}}$

d. $\frac{i}{A}$

72: of battery. Potential drop across terminals an external resistance R = r (internal resistance) connected across it is

a. $\epsilon/2$

b. $\epsilon/4$

c. $4\epsilon$

d. $2\epsilon$

73: Wire 1 has length L and a circular cross-section of diameter D. Wire 2 is constructed from same material as wire 1 and has same shape but its length is 2L. Resistance of wire 2 is

a. R/2

b. 2R

c. 4R

d. 9R

74: A battery that produces a potential difference V is connected to a 5W light bulb. Later, the 5W bulb is replaced with a 10W bulb. Battery supply greatest current in case of

a. 5W bulb

b. 10W bulb

c. Both bulbs are same

d. None

75: Two identical light bulbs are connected to a battery, either in series or parallel. Are the bulbs in series?

a. Dimmer as bulbs in parallel

b. Brighter as bulbs in parallel

c. Same brightness as bulbs in parallel

d. Nothing can be concluded

76: The direction of electric current produced by an electron that falls towards ground is

a. Downward

b. Upward

c. Towards left

d. Towards right

77: Differential form of conservation of charge is

a. $\vec{J}.\nabla=\partial\rho / \partial t$

b. $\mathbf{\nabla.\vec{J}=-\partial\rho/\partial t}$

c. $q=\int_{v}^{0}\rho dv$

d. None of these

78: An electron moving through a wire has an average drift speed that is very small. Does it mean that average velocity is almost equal to

a. Instantaneous velocity

b. Velocity of protons

c. Zero

d. None of above

79: A number of resistances are connected in series, which physical quantity remains constant?

a. Voltage

b. Current

c. Both a & b

d. None of these

80: The graph between potential difference and current for ohmic material will be:

a. Ellipse

b. Circle

c. Parabola

d. Straight line

81: An electron enters a magnetic field acting vertically downward with a velocity V from East. The electron is deflected along

a. South

b. Southeast

c. North

d. Northeast

83: A charged particle moves through a magnetic field in a direction perpendicular to it. Then the

a. Direction remains unchanged

b. Speed remains unchanged

c. Velocity remains unchanged

d. Acceleration remains unchanged

84: A paramagnetic material is kept in a magnetic field. The field is increased till the magnetization reaches saturation point. If temperature is now decreased, the magnetization will

a. Remains constant

b. Decrease

c. Increase

d. None

85: A particle moving in a magnetic field has an increase in its velocity then its radius of circle

a. Becomes half

b. Increases

c. Decreases

d. Remains same

86: A charged particle moves along a circle under action of possible electric and magnetic fields. Which of the following is possible?

a. $E=0,\ B=0$

b. $E\neq0,\ B=0$

c. $\mathbf{E=0,\ B\neq0}$

d. $E\neq0,B\neq0$

87: The force experienced by a charged particle in magnetic field is maximum when particle moves in a direction

a. Perpendicular to magnetic field

b. Parallel to magnetic field

c. Is at rest

d. None of above

88: Cathode rays enter in a uniform magnetic field perpendicular to direction of field. In magnetic field their path will be

a. Circle

b. Parabola

c. Straight-line

d. Ellipse

89: An alpha particle and proton having same momentum enter in a region of uniform magnetic field and move in circular paths. The ratio of radii of curvature of their paths in the field is

a. 2

b. 1

c. ½

d. ¼

90: A moving charge will produce

a. Only an electric field

b. Only a magnet field

c. Both electric and magnetic fields

d. No-field

91: A magnetic needle placed in a uniform magnetic field experience

a. A torque but not a force

b. A force but not a torque

c. A force and a torque

d. None of these

92: Current is following in two long parallel conductors is in the same direction. The conductors…………each other

a. Are inclined to

b. Attract

c. Repel

d. None of these

93: If relative permeability of a substance is 0.79, then it is …………. material

a. Diamagnetic

b. Paramagnetic

c. Ferromagnetic

d. None of these

94: A charged particle is moving in uniform magnetic field in a circular path. The radius of circular path is r. If energy of particle is doubled then new radius will be

a. 2r

b. $r/\sqrt2$

c. r/2

d. $\mathbf{r/\sqrt2}$

MCQ's with Answers

1: Two point charges are placed at some distance and force between them is F. If distance between two point charges is doubled, then electrostatic force between them is

2: A charged particle is placed in an electric field. The force on particle when its charge is doubled is

3: Electric flux through a surface depends upon

4: Two point charges at a certain distance r in air exert a force F on each other. The distance at which these charges will experience same force in a medium of relative permeability is

5: Two point charges repel each other with a force of 12N. If a charge of is given to each of these, then new force is

6: The magnitude of electric field such that an electron placed in it would experience an electric force equal to its weight is

7: A charge q is placed at centre of a cube, then electric flux through one face is

8: Two point charges q and –q situated at a distance d have force F. I f one charge is constant while other moves round the former in a circle of radius r, then work done is

9: A particle of mass m and charge q is thrown with a uniform speed v against an electric field E. The distance it will travel before coming to momentary rest is

10: A uniform electric field of 1N/C is set up by a uniform distribution of charge in the xy-plane. The electric field inside a metal ball placed 0.5m above the xy-plane is

11: If the distance between two charged objects is halved, then force between them becomes

12: A suspended object A is attracted to a neutral wall. It is also attracted to a positively charged object B. Which of the following is true about object A?

13: In which of the following contexts can Gauss’s law not be readily applied to find the electric field?

14: A circular ring of charge of radius r has a total charge q uniformly distributed around it. The magnitude to the electric field at the centre of the ring is

15: The direction of field lines around a negative charge q is

16: Electric flux through a closed surface depends upon

17: Magnitude of the flux of a constant electric field of in the x-direction through a rectangle with area in the yz-plane is

18: In Millikan experiment, the oil drop can be suspended between two plates when gravitational force is equal to

19: When 1020 electrons are removed from a neutral metal sphere then charge on sphere becomes

21: If value of ampere is reduced to half its present value, then value of as compared to its previous value will change

22: The potential at a point V(r) due to two charges located at positions is

23: A charged particle of mass m and charge q is released in an electric field of magnitude E. Its kinetic energy after time t is

24: If a charged spherical conductor of radius 10 cm has potential V at a point distant 5cm from its centre, then the potential at a point distant 15cm from centre will be

25: The electric field in a region is directed outwards and is proportional to distance r from origin. Taking electric potential at origin to be zero it is proportional to

26: A circular ring of radius r carries a charge q uniformly distributed on it. A small length dl is cut off. The electric field at centre due to remaining wire is

27: A uniform electric field pointing in x-direction exists in a region. Let A be origin, B a point at x=1cm and C, at y=1cm, then potential at points A, B and C satisfy

28: A charge q is placed at the centre of shell of radius r and another charge is placed on the shell. The potential at x = r/2 is

29: Two equal point charges are at on x-axis. Another point charge q is placed at the origin. The change in electrical potential energy of when it is displaced at a small distance r along the x-axis is approximately proportional to

30: Two copper spheres of same radii one hollow and other solid are charged to same potential, then

31: Charge q each are placed at (0, a,0) & (0, -a,0) and a charge –q is placed at (5a,0,0), then motion is

32: The potential at a point is being constant. Electric field vector is

33: The potential on surface of a charged metallic sphere of radius 5cm is 10V. The potential at centre of sphere will be

34: The work done on a unit positive charge in bringing it from infinity to any point is called

35: The potential difference between two points can be written as

36: The dimensions of potential are same as that of

38: A point charge q located at origin. The amount of work done in bringing a unit positive charge from infinity to origin is

39: Net force on a dipole in a uniform electric field is

41: A parallel plate capacitor of capacitance C is charged using a battery of . After capacitor is charged, the battery is removed and distance between capacitors is double, then the energy stored is

42: Three capacitors of each are to be connected in such a way that the net capacitance is . Then

43: Three capacitors of each are to be connected in series. The equivalent capacitance will be

44: If diameter of Earth is 12800km, then its capacitance will be

45: The electric energy density between plates of charged capacitor is

46: When dielectric medium of constant is filled between the plates of a charged parallel plate capacitor, then energy stored becomes, as compared to previous value

47: The capacitance of a parallel plate capacitor is . If a dielectric material of dielectric constant 16 is placed between the plates, then new capacitance is

48: A parallel plate capacitor has capacitance C. The separation between plates is doubled and a dielectric medium is introduced between the plates. If capacity now becomes 2C, dielectric constant of medium is

49: If we increase distance between two plates of capacitor, then capacitance will

50: A parallel plate capacitor is first charged and then dielectric slab is introduced between plates. The quality that remains unchanged is

51: Which material sheet should be placed between plates of parallel capacitor in order to increase its capacitance?

52: Farad is not equivalent to

53: There is an air filled parallel plate capacitor. When plate separation is doubled and the space is filled with wax, the capacitance increases to . The dielectric constant of wax is

54: Two metallic spheres of capacitances respectively carry some charges. They are brought in contact and then separated. The final charges on them will satisfy the relation

55: A charge q is placed at mid-point of line joining two equal charges Q. The system of three charges will be in equilibrium when q has value

56: Net charge on capacitor is

57: A 100µF capacitor is charged to 200V. It is discharged through resistance. The amount of heat generated will be

58: The capacitance of parallel plate capacitor in air is . If dielectric medium is placed then potential difference reduces to 1/6 of original value. The dielectric constant of material is

59: A cylindrical capacitor has radii The amount of energy stored in a cylinder of radius is …………. of total energy

60: A thin material plate is used in between a parallel plate capacitor having capacitance C, then new capacitance C’ is

61: A given battery is rated as 250ampere-hours. This rating indicates which of the following quantities that can be drawn from battery

62: A conducting wire is quadrupled in length and tripled in diameter, then its resistance

63: If wire of resistance R is stretched to double its length, its resistance becomes

65: Two wires of same material having lengths L and 2L and cross-sectional area 4A and A respectively. The ratio of their specific resistances would be

66: The resistance of a conductor at absolute zero (0K) is

67: A steady current flows in a metallic conductor of non-uniform cross-section. The quantity/quantities constant along length of conductor is/are

68: The resistance of a wire is R. It is cut into four equal parts and bounded together in parallel. The equivalent resistance will be

69: Two wires of same materials have same length but their areas are in ratio 3:1. The two wires are connected in series. The resistance of thicker wire is . Total resistance of combination is

70: A copper wire is connected across a battery. The drift velocity of electron is . If another wire of same length and double the radius is connected across same battery, then drift velocity will be

71: If resistivity of potentiometer wire be and of cross-section be A. If is current through potentiometer wire, then potential gradient along wire will be

72: of battery. Potential drop across terminals an external resistance R = r (internal resistance) connected across it is

73: Wire 1 has length L and a circular cross-section of diameter D. Wire 2 is constructed from same material as wire 1 and has same shape but its length is 2L. Resistance of wire 2 is

74: A battery that produces a potential difference V is connected to a 5W light bulb. Later, the 5W bulb is replaced with a 10W bulb. Battery supply greatest current in case of

75: Two identical light bulbs are connected to a battery, either in series or parallel. Are the bulbs in series?

76: The direction of electric current produced by an electron that falls towards ground is

77: Differential form of conservation of charge is

79: A number of resistances are connected in series, which physical quantity remains constant?

80: The graph between potential difference and current for ohmic material will be:

81: An electron enters a magnetic field acting vertically downward with a velocity V from East. The electron is deflected along

83: A charged particle moves through a magnetic field in a direction perpendicular to it. Then the

84: A paramagnetic material is kept in a magnetic field. The field is increased till the magnetization reaches saturation point. If temperature is now decreased, the magnetization will

85: A particle moving in a magnetic field has an increase in its velocity then its radius of circle

19: When 10²⁰ electrons are removed from a neutral metal sphere then charge on sphere becomes