Free NEET Physics multiple-choice questions on Electric Field & Dipole. Attempt each question and reveal the answer with a full explanation.
Which of the following molecules is a polar molecule? HCl O 2 N 2 CH 4 The electric potential at a point on the equatorial plane of an electric dipole of dipole moment p is: Zero 1 4 0 p r 2 1 4 0 p r Infinite If the electric potential at the surface of a hollow allowed sphere of radius R is V , then the potential at the centre of the sphere is: V Zero V/2 2V A thin spherical shell of radius R has charge Q spread uniformly over its surface. Which of the following graphs most closely represents the electric field E(r) produced by the shell in the range 0 r < ? E is zero for r < R, and decreases as 1/r² for r > R E increases linearly for r < R, and decreases as 1/r² for r > R E is constant for r < R, and decreases as 1/r² for r > R E is zero for r < R, and decreases as 1/r for r > R The work done in rotating an electric dipole of dipole moment p from the direction of the electric field E by 180 is: 2pE pE zero -2pE Which of the following is NOT a property of equipotential surfaces? They can intersect each other at right angles The work done in moving a charge over them is zero Electric field lines are always perpendicular to them For a uniform electric field, they are concentric planes The electric potential at a point P at a distance r from the center of a dipole of moment p is V . If the distance is doubled, the potential will be: V/4 V/2 V/8 2V In a region of space, the electric field is zero. This implies that the electric potential in this region is: constant zero linearly increasing linearly decreasing The electric field at a distance r from an infinitely long straight wire of linear charge density λ is E 1 . The electric field at distance 2r from the same wire is E 2 . The relation between E 1 and E 2 is: E 1 = 2E 2 E 1 = E 2 E 1 = E 2/2 E 1 = 4E 2 An electric dipole of moment p is placed in a uniform electric field E . If the dipole is rotated through a small angle from its equilibrium position, the restoring torque is proportional to: 2 1 A hollow metal sphere of radius R is given a charge Q . The potential at the center of the sphere is: 1 4 0 Q R Zero 1 4 0 Q 2R Infinite Which of the following statement is false for electric field lines? They can form closed loops They start from positive and end at negative charges They do not intersect each other They are continuous curves in a charge-free region The electric field lines of a positive point charge are: Radially outwards Radially inwards Circular clockwise Circular anti-clockwise Which of the following quantity is a vector? Electric field intensity Electric potential Electric flux Capacitance An electric dipole of moment p is lying along a uniform electric field E . The work done in rotating the dipole by 90 is: pE √ 2 pE pE/2 2pE In a region of constant potential V = 100 V, the electric field is: Zero 100 V/m 1 V/m Infinite A soap bubble is charged to a potential 16 V. If its radius is doubled, its new potential will be: 8 V 4 V 32 V 16 V The electric field required to keep a water drop of mass m and charge e suspended in air is: mg/e e/mg mge mg Four point charges -Q, -q, 2q and 2Q are placed, one at each corner of the square. The relation between Q and q for which the potential at the centre of the square is zero is: Q = -q Q = q Q = -2q Q = 2q A point P lies on the perpendicular bisector of an electric dipole of dipole moment p . If the distance of P from the dipole is r (much larger than the size of the dipole), then the electric field at P is proportional to: p and r -3 p and r -2 p -1 and r -2 p and r -1 A square surface of side L metres is in the plane of the paper. A uniform electric field E (volt/m), also in the plane of the paper, is limited only to the lower half of the square surface, (see figure). The electric flux in SI units associated with the surface is:- EL 2 2 0 EL 2 2 Zero EL 2 A hollow metal sphere of radius R is uniformly charged. The electric field due to the sphere at a distance r from the centre Decreases as r increases for r < R and for r > R Increases as r increases for r < R and for r > R Zero as r increases for r < R, decreases as r increases for r > R Zero as r increases for r < R, increases as r increases for r > R An electron enters a uniform electric field E with a velocity v perpendicular to the field. The path of the electron will be: Parabolic Circular Straight line Elliptical If s E d S =0 over a surface, then The number of flux lines entering the surface must be equal to the number of flux lines leaving it The magnitude of electric field on the surface is constant All the charges must necessarily be inside the surface The electric field inside the surface is necessarily uniform Potential energy of an electric dipole in a uniform electric field is minimum when the angle between the dipole moment and electric field is: 0 90 180 45 The electric potential V at any point (x, y, z) is given by V = 3x 2 . The electric field at point (2, 0, 1) is: -12 i 12 i -6 i 6 i A dipole is placed in a non-uniform electric field. It experiences: both a net force and a torque only a net force only a torque neither a net force nor a torque The work done in rotating an electric dipole of dipole moment p from its position of stable equilibrium to unstable equilibrium in a uniform electric field E is: 2pE pE zero -pE Three point charges +q, -2q and +q are placed at points (x=0, y=a, z=0) , (x=0, y=0, z=0) and (x=a, y=0, z=0) respectively. The magnitude of the net electric dipole moment of this system is: 2 qa qa 2qa zero Two point charges +q and -q are held fixed at (-d, 0) and (d, 0) respectively of a x-y coordinate system. Then: The electric field E at origin points towards (d, 0) The electric field E at origin is zero The electric potential V at origin is non-zero The electric field E at origin points towards (-d, 0) An electric dipole is placed at an angle of 60 with a uniform electric field of magnitude 4 10 5 N/C . It experiences a torque of 8 3 Nm . If the dipole length is 2 cm , the magnitude of the charge on the dipole is: 2 mC 8 mC 5 mC 7 C A metallic solid sphere is placed in a uniform electric field. The lines of force follow the path(s) shown in the figure: Path 4 (Entering and leaving perpendicular to surface, zero field inside) Path 1 (Passing straight through) Path 2 (Curved but passing through center) Path 3 (Entering perpendicularly but non-zero field inside) Which of the following does not have the units of electric field? J/C V/m N/C J/(C m) Two hollow conducting spheres of radii R 1 and R 2 ( R 1 R 2 ) have equal charges. The potential would be: more on smaller sphere more on bigger sphere equal on both spheres dependent on the material of the spheres What is the angle between the electric dipole moment and the electric field on the equatorial line of a dipole? 180 0 90 45 A point charge -q is revolving around a fixed charge +Q in a circle of radius r . The time period of revolution is proportional to: r 3/2 r 2 r r 1/2 An electric dipole is placed at an angle of 30 with an electric field intensity 2 10 5 N/C . It experiences a torque equal to 4 Nm . The charge on the dipole, if the dipole length is 2 cm , is: 2 mC 5 mC 7 C 8 mC The electric field intensity at a distance r from the center of a uniformly charged non-conducting solid sphere of radius R ( r < R ) varies as: r 1 1 r 2 1 r Independent of r A square of side a has four charges +q, +q, -q, -q placed at its corners in clockwise order. The electric field at the center of the square is: Perpendicular to one of the sides Along the diagonal joining +q and -q Zero Radially outwards What is the angle between the electric dipole moment p and the electric field E at a point on the axial line? 0 90 180 270 The electric potential V as a function of distance x is shown in the figure. The electric field is zero at: x = 2 m x = 1 m x = 3 m Everywhere An electric dipole is placed at an angle of 30 with an electric field intensity 2 10 5 N/C . It experiences a torque equal to 4 Nm . The charge on the dipole, if the dipole length is 2 cm , is: 2 mC 8 mC 5 mC 7 μ C Two parallel infinite line charges with linear charge densities + λ C/m and - λ C/m are placed at a distance of 2R in free space. What is the electric field mid-way between the two line charges? λ πε 0 R λ 2 πε 0 R Zero 2 λ πε 0 R A spherical conductor of radius R is charged with Q . The variation of electric field E with distance r from the centre of the sphere is correctly represented by: E = 0 for r < R and E 1/r 2 for r > R E r for r < R and E 1/r 2 for r > R E = 0 for r < R and E 1/r for r > R E 1/r 2 for all r A spherical conductor of radius 10 cm has a charge of 3.2 10 -7 C distributed uniformly. What is the magnitude of electric field at a point 15 cm from the centre of the sphere? 1.28 10 5 N/C 1.28 10 4 N/C 1.28 10 6 N/C 1.28 10 7 N/C An electric dipole consists of two opposite charges of 2 10 -6 C separated by a distance of 3 cm . It is placed in an electric field of 2 10 5 N/C . The maximum torque on the dipole is: 1.2 10 -2 Nm 0.6 10 -2 Nm 2.4 10 -2 Nm 1.2 10 -3 Nm The electric potential at a point on the axis of an electric dipole at a distance r from its centre is V . If the distance is doubled, the potential becomes: V/4 V/2 V/8 2V The ratio of the electric field at a point on the axis and at a point on the equatorial line of a short dipole at the same distance r from the centre is: 2 : 1 1 : 2 4 : 1 1 : 1 An electric dipole is placed in a non-uniform electric field. It experiences: Both a force and a torque Only a force Only a torque Neither force nor torque A hollow cylinder has a charge q coulomb within it. If is the electric flux in units of voltmeter associated with the curved surface B, the flux linked with the plane surface A in units of voltmeter will be q 2 0 3 q 0 - 1 2 ( q 0 - ) Two parallel infinite line charges with linear charge densities + C/m and - C/m are placed at a distance of 2R in free space. What is the electric field mid-way between the two line charges? 2 0 R N/C Zero 2 0 R N/C 0 R N/C Two thin dielectric slabs of dielectric constants K 1 and K 2 ( K 1 < K 2 ) are inserted between the plates of a parallel plate capacitor. The variation of electric field E with distance x as measured from the positive plate is correctly shown by: Field is lower in the slab with higher K Field is higher in the slab with higher K Field is independent of K Field is zero inside slabs Three point charges +q, -2q and +q are placed at points (x=0, y=a, z=0) , (x=0, y=0, z=0) and (x=a, y=0, z=0) respectively. The magnitude and direction of the electric dipole moment vector of this charge assembly are: 2 qa along the line joining points (0,0,0) and (a,a,0) qa along the line joining points (0,0,0) and (a,a,0) 2 qa along the x-axis 2 qa along the y-axis The electric potential at a point (x, y, z) is given by V = -x 2y - xz 3 + 4 . The electric field E at that point is: (2xy + z 3) i + x 2 j + 3xz 2 k (2xy - z 3) i + x 2 j + 3xz 2 k (2xy + z 3) i - x 2 j - 3xz 2 k (-2xy - z 3) i - x 2 j - 3xz 2 k Three point charges q, -2q and q are placed at vertices of an equilateral triangle of side a . The electric dipole moment of the system is: 3 qa 2qa qa Zero A spherical conductor of radius R has a uniform charge Q . The electric field E and potential V at a distance r ( r < R ) from the center are: E = 0, V = kQ R E = 0, V = 0 E = kQ R 2 , V = 0 E = kQ r 2 , V = kQ r The electric potential in a region is V = 6x - 8xy 2 - 8y + 6yz - 4z 2 . The force experienced by a charge of 2 C at point (1, 1, 1) is: 4 35 N 24 N 10 N 20 N The electric field at a point on the equatorial plane of a dipole is E 1 . If the distance of the point from the center of the dipole is doubled, the new electric field E 2 will be: E 1/8 E 1/4 E 1/2 E 1/16 Which of the following graphs represents the variation of electric field E with distance r for a line charge? E 1/r E 1/r 2 E r E is constant In a certain region of space, the electric potential is found to be constant throughout. The electric field in this region is: Zero Uniform but non-zero Varying with distance Inversely proportional to distance