ELECTRO STATICS
- Two charges q1 and q2 are separated by a distance d. What is the electric field at a point P on the perpendicular bisector of the line joining the charges? (a) kq1q2/d^3 (b) kq1q2/d^2 (c) 2kq1q2/d^3 (d) 2kq1q2/d^2 Answer: (a) kq1q2/d^3
- The electric potential at a point P due to a point charge Q located at a distance r from P is V. What is the electric potential at a point P' located at a distance 2r from Q? (a) V/2 (b) V/4 (c) V/8 (d) V/16 Answer: (d) V/16
- A metallic sphere of radius 10 cm is charged with 10 μC of charge. What is the electric field at a distance of 5 cm from the center of the sphere? (a) 8.99 x 10^6 N/C (b) 4.50 x 10^6 N/C (c) 1.80 x 10^6 N/C (d) 0.90 x 10^6 N/C Answer: (b) 4.50 x 10^6 N/C
- Two point charges of magnitude 2 μC and -4 μC are placed 30 cm apart in air. What is the electric field at a point on the line joining the charges, at a distance of 20 cm from the positive charge? (a) 2.4 x 10^4 N/C (b) 4.8 x 10^4 N/C (c) 7.2 x 10^4 N/C (d) 9.6 x 10^4 N/C Answer: (d) 9.6 x 10^4 N/C
- Two charges of +q and -q are separated by a distance of 2a. What is the electric field at a point on the line joining the charges, at a distance of a from the positive charge? (a) kq/a^2 (b) 2kq/a^2 (c) 3kq/a^2 (d) 4kq/a^2 Answer: (a) kq/a^2
- Three charges of +q, +q, and -q are placed at the vertices of an equilateral triangle of side a. What is the electric potential energy of the system? (a) -3kq^2/a (b) -kq^2/a (c) 0 (d) kq^2/a Answer: (d) kq^2/a
- An electric field of 10^6 N/C is applied to a spherical conductor of radius 1 cm. What is the charge induced on the surface of the conductor? (a) 4πε0 x 10^-6 C (b) 4πε0 x 10^-9 C (c) 4πε0 x 10^-12 C (d) 4πε0 x 10^-15 C Answer: (a) 4πε0 x 10^-6 C
- Two identical metallic spheres, A and B, each carrying a charge of +Q, are separated by a distance d in air. If the spheres are now connected by a thin wire, then what will be the final charge on each sphere? (a) 0.5 Q (b) Q (c) 2 Q (d) 4 Q Answer: (a) 0.5 Q
- A charged particle of charge q is moved from point A to point B in an electric field. If the electric potential difference between the points A and B is V, then the work done in moving the charge is: (a) qV (b) -qV (c) V/q (d) -V/q Answer: (a) qV
- Two identical metallic spheres, A and B, each carrying a charge of +Q, are separated by a distance d in air. A third identical sphere, C, is brought in contact with A and then placed at a distance d/2 from B. What will be the force between the spheres B and C? (a) Q^2/8πε0d^2 (b) Q^2/πε0d^2 (c) Q^2/4πε0d^2 (d) Q^2/2πε0d^2 Answer: (c) Q^2/4πε0d^2
- A charge of 20 μC is placed at the center of a cube of side 10 cm. What is the electric flux through one face of the cube? (a) 0 (b) 2.25 x 10^6 Nm^2/C (c) 2.5 x 10^6 Nm^2/C (d) 2.75 x 10^6 Nm^2/C Answer: (b) 2.25 x 10^6 Nm^2/C
- Which of the following is a scalar quantity? a) Electric field b) Electric potential c) Electric flux d) Electric potential energy Answer: b) Electric potential
- Two point charges of +2 C and -3 C are separated by a distance of 10 cm. What is the force between them? a) 1.8 x 10^9 N b) 2.4 x 10^-9 N c) 9 x 10^9 N d) 3 x 10^9 N Answer: d) 3 x 10^9 N (Using Coulomb's law, F = kq1q2/r^2 = 9 x 10^9 * 2 * 3 / 0.1^2 = 3 x 10^9 N)
- A point charge of +5 μC experiences a force of 10 N in an electric field. What is the strength of the electric field at the point? a) 5 x 10^3 N/C b) 2 x 10^3 N/C c) 1 x 10^3 N/C d) 0.5 x 10^3 N/C Answer: c) 1 x 10^3 N/C (Using E = F/q = 10/5 x 10^-6 = 2 x 10^3 N/C)
Electric field at a point due to a point charge Q varies as: A) 1/r^2 B) 1/r C) r^2 D) r Answer: A
Coulomb’s law is similar to: A) Newton’s law of motion B) Archimedes’ principle C) Pascal’s law D) Faraday’s law Answer: A
The electric field inside a charged conducting sphere is: A) uniform and zero B) non-uniform and zero C) zero but not uniform D) uniform but not zero Answer: A
Electric flux is: A) a scalar quantity B) a vector quantity C) both scalar and vector quantity D) neither scalar nor vector quantity Answer: A
Electric field lines are: A) always closed curves B) always straight lines C) always circular arcs D) none of the above Answer: B
Electric potential is: A) a vector quantity B) a scalar quantity C) both vector and scalar quantity D) none of the above Answer: B
The electric potential inside a charged conducting sphere is: A) zero B) non-zero but constant C) non-zero and non-constant D) none of the above Answer: B
The potential energy of two charges separated by a distance ‘r’ is: A) directly proportional to r B) inversely proportional to r C) proportional to r^2 D) proportional to 1/r^2 Answer: D
The electric field due to an infinite plane sheet of charge is: A) zero B) non-zero and constant C) non-zero and non-constant D) none of the above Answer: B
The capacitance of a parallel plate capacitor is: A) directly proportional to the area of the plates B) inversely proportional to the distance between the plates C) proportional to the charge on the plates D) all of the above Answer: D
The work done in moving a charge q from one point to another is given by: A) ΔV/q B) q/ΔV C) qV D) V/q Answer: A
The SI unit of electric potential is: A) Joule/Coulomb B) Volt/Coulomb C) Watt/Second D) Watt/Coulomb Answer: B
The electric potential at a point due to a point charge Q varies as: A) 1/r^2 B) 1/r C) r^2 D) r Answer: B
Electric field due to an electric dipole at a point on the axial line is proportional to: A) 1/r B) 1/r^2 C) r D) r^2 Answer: B
The force between two charges is: A) directly proportional to the product of the charges B) inversely proportional to the square of the distance between the charges C) directly proportional to the permittivity of the medium D) all of the above Answer: D
Electric potential energy of a charged sphere is: A) positive B) negative C) zero D) depends on the charge Answer: A
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