83 free MCQs on Electric Charges and Fields, each with its own worked answer and explanation. Coulomb's law, electric field, potential, capacitors, Gauss's law.
Take the timed Electric Charges and Fields chapterwise test →83 practice questions on Electric Charges and Fields, sorted Easy → Hard. Try each one first, then open its answer page for the worked explanation. Want the full theory first? Read the Electric Charges and Fields notes.
Field lines always point from positive to negative charge, are denser where the field is stronger, and never cross; an isolated positive charge has lines radiating symmetrically outward, while a dipole's lines curve from the positive to the negative charge.
Q1.
Two point charges of +2 µC and +3 µC are separated by 0.3 m in vacuum. The magnitude of the electrostatic force between them is:
Q2.
An object gains 5 × 10<sup>12</sup> electrons. Its net charge is:
Q3.
Two charges +2 µC and -3 µC are separated by 0.3 m. Their electrostatic potential energy is:
Q4.
A positive charge is moved along an equipotential surface. The work done by the electric field is:
Q5.
For two equal positive charges placed symmetrically about a point, the electric field at the midpoint is zero because:
Q8.
Charge on an electron is:
Q9.
Coulomb's law: force between charges q<sub>1</sub> and q<sub>2</sub> at distance r:
Q10.
Electric field lines originate from:
Q11.
Electric field due to a point charge Q at distance r:
Q12.
Inside a conductor in electrostatic equilibrium, electric field is:
Q14.
Equipotential surfaces are always _____ to electric field lines:
Q15.
Electric potential due to a point charge decreases as:
Q16.
A hollow conductor placed in an external field: the interior has:
Q17.
Two like electric charges placed near each other:
Q18.
Two unlike electric charges placed near each other:
Q19.
The SI unit of electric charge is the:
Q20.
The charge carried by an electron is:
Q21.
The charge carried by a proton is:
Q22.
Electric charge is quantised, meaning it can only be:
Q23.
An object carrying equal positive and negative charge is electrically:
Q24.
The region around a charge in which it exerts a force is called the:
Q25.
Electric field lines begin on ___ charges:
Q26.
A point charge of 8 µC lies inside a closed surface. The net electric flux through the surface is (take ε<sub>0</sub> = 8.85 × 10<sup>-12</sup> C<sup>2</sup> N<sup>-1</sup> m<sup>-2</sup>):
Q27.
Two positive charges q and 4q are separated by a distance d. The point between them where the net electric field is zero is at a distance from q equal to:
Q28.
Two charges +2 µC and -6 µC are separated by 0.4 m. The electric potential at the midpoint is:
Q29.
An infinitely long straight wire has a uniform linear charge density of 4 × 10<sup>-9</sup> C/m. The electric field at a distance of 0.2 m from the wire is approximately:
Q30.
A short electric dipole has dipole moment 4 × 10<sup>-8</sup> C m. At a point 0.2 m away on its axial line, the far-field electric potential is approximately:
Q31.
Two charges of +4 C and -1 C are 3 m apart. Force between them (k = 9 x 10<sup>9</sup>):
Q32.
Electric field between two parallel plates (surface charge density sigma, area A):
Q33.
A charge +Q is inside a closed surface. Total outward flux:
Q34.
Electric field at surface of a charged conductor with surface charge density sigma:
Q35.
Torque on an electric dipole of moment p in uniform field E:
Q36.
Coulomb’s law says the force between two charges is inversely proportional to the ___ of the distance between them:
Q37.
The electric field due to a point charge q at a distance r is:
Q39.
The direction of the electric field is the direction of the force on a ___ test charge:
Q40.
Two electric field lines can never:
Q41.
The relation between the flux through a closed surface and the charge it encloses is given by ___ law:
Q42.
An electric dipole consists of two equal and opposite charges separated by a small:
Q43.
The electric dipole moment points from the ___ charge to the ___ charge:
Q44.
The electric field inside a charged hollow conductor is:
Q45.
If both charges are doubled, the Coulomb force between them becomes ___ times the original:
Q46.
If the distance between two charges is doubled, the force becomes ___ of the original:
Q47.
Electric flux is a measure of the number of field lines passing through a:
Q48.
The SI unit of electric flux is:
Q49.
The electric field inside a conductor in electrostatic equilibrium is:
Q50.
A pair of +2 μC and −2 μC charges a small distance apart forms an electric:
Q51.
Two point charges +2 µC and -8 µC are 3 m apart. The point between them where the net electric field is zero is 1 m from the +2 µC charge. The electric potential at this point is:
Q52.
Three charges, +q, +q and -q, are placed at the vertices of an equilateral triangle of side 0.2 m. If q = 2 µC, the total electrostatic potential energy of the system is:
Q53.
A charge q is placed at one vertex of a cube. The electric flux through each of the three faces that do not contain that vertex is:
Q54.
A dipole of moment 3 × 10<sup>-8</sup> C m is rotated in a uniform electric field of 2 × 10<sup>5</sup> N/C from 60° to 120°. The increase in its potential energy is:
Q55.
A uniformly charged thin spherical shell has charge Q and radius R. A point P is located at a distance 2R from its centre. Compared with the potential at the surface, the potential at P is:
Q56.
A uniformly charged thin shell of radius R and charge Q. Electric field at r < R:
Q57.
Work done to bring charge q from infinity to surface of charged sphere of radius R and charge Q:
Q58.
Five equal charges Q are placed at 5 corners of a regular hexagon. Electric field at center due to 5 charges:
Q59.
Charge Q is distributed uniformly on a sphere of radius R. At distance r > R, electric field:
Q60.
Electric field inside a uniformly charged solid sphere at distance r from center (R = radius, Q = total charge):
Q61.
The force between two 1 C charges placed 1 m apart is approximately:
Q62.
By Gauss’s law, the total electric flux through a closed surface enclosing a charge Q is:
Q63.
The electric field due to an infinitely long straight charged wire varies with distance r as:
Q64.
The electric field due to an infinite charged plane sheet is:
Q65.
The torque on an electric dipole of moment p placed in a uniform field E is:
Q66.
The potential energy of a dipole in a field is minimum when the dipole is aligned ___ the field:
Q67.
On the axis of a short electric dipole, the field falls off with distance as:
Q68.
Two identical charges q are 2r apart. The electric field exactly at the midpoint is:
Q69.
The number of electrons that make up a charge of 1 coulomb is about:
Q70.
A charge Q sits at the centre of a cube. The electric flux through one face is:
Q71.
Electric field is a ___ quantity:
Q72.
Coulomb’s law has the same inverse-square form as ___ law of gravitation:
Q73.
When a dielectric medium is placed between two charges, the force between them:
Q74.
The work done in rotating a dipole from parallel to perpendicular to a field E is:
Q75.
The net electric flux through a closed surface that encloses no net charge is:
Q76.
Two charges attract with force F in vacuum. When the same charges are placed in a medium of dielectric constant 2 at the same separation, the force becomes:
Q77.
For a short dipole, the ratio of the electric field on its axis to the field on its equator at the same distance is:
Q78.
A point charge q is placed at the centre of a cube. The electric flux through one face of the cube is:
Q79.
The electric field inside a uniformly charged solid conducting sphere (in electrostatic equilibrium) is:
Q80.
Two equal positive charges +q are separated by a distance d. The electric field at the midpoint of the line joining them is:
Q81.
An electric dipole in a uniform electric field experiences maximum torque when the angle between the dipole moment and the field is:
Q82.
An electron is placed in a uniform electric field of 1000 N/C. Its acceleration (e = 1.6×10⁻¹⁹ C, m = 9.1×10⁻³¹ kg) is about:
Q83.
A uniform electric field of 2×10³ N/C passes perpendicularly through a flat surface of area 0.5 m². The electric flux is:
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