Title 01. ELECTRIC CHARGES AND FIELDS.pdf ✅

01. ELECTRIC CHARGES AND FIELDS NEET PREPARATION (MEDIUM PHYSICS PAPER) Date: March 12, 2025 Dura on: 1:00:00 Total Marks: 180 INSTRUCTIONS INSTRUCTIONS PHYSICS 1. Electric charges are placed at the corners of an equilateral of side . The magnitude of electric dipole moment of the sys‐ tem is (1) (2) (3) (4) 2. Two particles of equal mass and charge are placed at a distance of 16 . They do not expe‐ rience any force. The value of is (1) (2) (3) (4) 3. The force of repulsion between two identical positive charges when kept with a separation in air is . Half the gap between the two charges is filled by a dielectic slab of dielectric constant 16.Then the new force of repulsion between those two charges becomes (1) (2) (3) (4) 4. The electric field in a region of space is given by, where . The flux of the field through a circular surface of ra‐ dius parallel to the plane is nearly: (1) (2) (3) (4) 5. The parallel plane sheets 1 and 2 carry uniform charge densities as shown in the fig‐ ure. The magnitude of the resultant electric field in the region marked III is (1) (2) (3) (4) 6. A point charge of is placed at the origin. At what location on the -axis should a point charge of be placed so that the net electric field is zero at on the -axis? (1) (2) (3) (4) 7. Assertion : Gauss's law can't be used to calculate electric field near an electric dipole. Reason : Electric dipole does not have symmetrical field. (1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. (3) Assertion is cor- rect but Reason is incorrect. (4) Assertion is incor- rect but reason is correct. 8. Assertion : If an electron and proton possessing same kinetic energy enter an electric field in a perpendicular direction, their paths will be curved. 2q, 2q, −4q Δ ABC l ql √3 ql 2√3ql √2 ql m q cm q m √ πε0 G √ G 4πε0 √πε0G √4πε0G r F F 3 2F 3 4F 3 4F 25 E→ = E0 ^i + 2E0 ^j E0 = 100N/C 0.02 m Y − Z 0.125 Nm2/C 0.02 Nm2/C 0.005 Nm2/C 3.14 Nm2/C σ1 and σ2 (σ1 > σ2) σ1 +σ2 2ε0 σ2 2ε0 σ1σ2 ε0 σ1 2σ2ε0 10 μC X 40 μC x = 2 cm X x = −4 cm x = 4 cm x = 8 cm x = 6 cm
Reason : Electron curves aways from the field. (1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. (3) Assertion is cor- rect but Reason is incorrect. (4) Assertion is incor- rect but reason is correct. 9. Two charges each of magnitude and sepa‐ rated by a distance of constitute an elec‐ tric dipole.If the dipole is placed in an uniform electric field ' ' of making angle with , the magnitude of torque acting on dipole is (1) (2) (3) (4) 10. Assertion : If a conducting medium is placed between two charges, then electric force between them be‐ comes zero. Reason : Reduction in a force due to introduced material is inversely proportional to its dielectric con‐ stant. conductor is not dielectric. (1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. (3) Assertion is cor- rect but Reason is incorrect. (4) Assertion is incor- rect but reason is correct. 11. What is the angle between the electric dipole moment and the electric field strength due to it on the equatorial line? (1) (2) (3) (4) None of these 12. The parallel plane sheets 1 and 2 carry uniform charge densities as shown in the fig‐ ure. The magnitude of the resultant electric field in the region marked II is (1) (2) (3) (4) 13. Two copper balls, each weighing 10 are kept in air 10 apart. If one electron from every atoms is transferred from one ball to the other, the coulomb force between them is (atomic weight of copper is ) (1) (2) (3) (4) 14. A charge is placed at the centre of a cube. The electric flux through any two consecutive faces will be (1) (2) (3) (4) 15. Assertion : Electric lines of force do not cross each other. Reason : Electric field at a point does not superimpose to give one resultant electric field. (1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. (3) Assertion is cor- rect but Reason is incorrect. (4) Assertion is incor- rect but reason is correct. 16. The electric field in a region is given by with Find the flux of this field through a rectangular surface of area par‐ allel to the - plane. (1) (2) (3) (4) None of these 17. Assertion : In a cavity within a conductor, the electric field is zero. Reason : Charges in a conductor reside only at its surface. (1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. 0.01C 0.4 mm E→ 10dyne/C 30 ∘ E→ 1.0 × 10 −8Nm 1.5 × 10 −9Nm 4.0 × 10 −10Nm 2.0 × 10 −10Nm 0 ∘ 90 ∘ 180 ∘ σ1 and σ2 (σ1 > σ2) (σ1 +σ2) 2ε0 −(σ1 σ2) 2ε0 − (σ1 +σ2) 2ε0 (σ1 −σ2) 2ε0 g cm 10 6 63.5g 2.0 × 10 6N 2.0 × 10 4N 2.0 × 10 10N 2.0 × 10 8N q πq 6 (4πε0) q 6 (4πε0) 2πq 6 (4πε0) 4πq 3 (4πε0) → E = E0 ^i + E0 ^j + E0 3 k^ 5 3 2 E0 = 2 × 10 3NC −1 . 0.2m2 Y Z 320Nm2C−1 240Nm2C−1 400Nm2C −1
(3) Assertion is cor- rect but Reason is incorrect. (4) Assertion is incor- rect but reason is correct. 18. A charged particle of mass and charge enters in an electric field of . Then its kinetic energy after is (1) (2) (3) (4) 19. Assertion : A small metal ball is suspended in a uniform electric field with the help of an insulated thread. When a high energy rays beam falls on the ball. Then the ball will be defected in the direc‐ tion of electric field. Reason : The ball will oscillate in the field. (1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. (3) Assertion is cor- rect but Reason is incorrect. (4) Assertion is incor- rect but reason is correct. 20. Four point charges are placed on the corners of a square of side length ‘ ’ as shown in the figure. The magnitude of the electric field at a point which is at a distance from the centre along a line perpendic‐ ular to the plane of the square and passing through the centre is, (1) (2) (3) (4) 21. A 2 gram object located in a region of uniform electric field carries a charge . The object released from rest at , has a kinetic energy of at . Then is (1) (2) (3) (4) 22. Assertion : A line of electrostatic force has sudden breaks. Reason : An electrostatic line of force is a continuous curve. (1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. (3) Assertion is cor- rect but Reason is incorrect. (4) Assertion is incor- rect but reason is correct. 23. Two conducting plates and are parellel to each other. is given a charge and is given a charge . The charge on inner side of is (1) (2) (3) (4) 24. A ring of radius carries a charge uniformly distributed over its length. A charge is placed at its centre will experience a force equal to (1) (2) (3) Zero (4) None of these 25. Two positive ions, each carrying a charge , are separated by a distance . If F is the force of re‐ pulsion between the ions, the number of elec‐ trons missing from each ions will be (e being the charge on an electron) (1) (2) (3) (4) 26. A body has a charge of . The number of excess electrons it has is (1) (2) (3) (4) 27. Assertion : Acceleration of charged particle in non-uniform electric field does not depend on velocity of charged particle. Reason : Charge is an invariant quantity. That is amount of charge on particle does not depend on frame of reference. 3 × 10 −3 Kg 6 × 10 −6 C 7 V /m 1 m 10 −4 J 9 × 10 −2 J 1.05 × 10 −3 J 4.2 × 10 −5 J X +q, +q, −q and − q a x(>> a) √2qa 4πεox3 qa 2πεox 3 √2qa 2πεox3 qa 4πεox 3 → E = (300 NC −1)^i Q x = 0 0.12 J x = 0.5 m Q 400 μC −400 μC 800 μC −800 μC A B A Q1 B Q2 B Q1−Q2 2 (Q2−Q1) 2 (Q1+Q2) 2 −(Q1+Q2) 2 r Q q qQ 8πε0r 3 qQ 4πε0r 2 q d 4πε0Fd 2 d 2 √ 4πε0Fd 2 e √ 4πε0Fd 2 e 2 4πε0Fd 2 q 2 −3.2μC 5.12 × 10 25 5 × 10 12 2 × 10 13 5.12 × 10 13
(1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. (3) Assertion is cor- rect but Reason is incorrect. (4) Assertion is incor- rect but reason is correct. 28. Two spheres of electric charges and are placed at a distance apart. If they are allowed to touch each other, what is the new distance between them to get a repulsive force of same magnitude as before? (1) (2) (3) (4) 29. The point charges and are placed some distance apart. If the electric field at the location of is , then the electric field at the location of will be (1) (2) (3) (4) 30. Force of attraction between two point electric charges placed at a distance in a medium is . What distance apart should these be kept in the same medium, so that force between them be‐ comes ? (1) (2) (3) (4) 31. Electric charges are distributed in a small vol‐ ume. The flux of the electric field through a spherical surface of radius 1 surrounding the total charge is 100 - . The flux over the con‐ centric sphere of radius 2 will be (1) (2) (3) (4) 32. Assertion : A metallic shield in form of a hollow shell may be built to block an electric field. Reason : In a hollow spherical shield, the electric field in‐ side it is zero at every point. (1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. (3) Assertion is cor- rect but Reason is incorrect. (4) Assertion is incor- rect but reason is correct. 33. A ring of charge with radius 0.5 has gap. If the ring carries a charge of , the electric field at the center is (1) (2) (3) (4) 34. A point charge is at a distance 5 di‐ rectly above the centre of a square of side 10 as shown in the figure What is the magnitude of the electric flux through the square ? (in ) (1) (2) (3) (4) 35. Assertion : Vehicle carrying highly inflammable materials have hanging chains, slightly touching the ground. Reason : The body of a vehicle gets charged when moving through air at high speed. (1) Both Assertion and Reason are cor- rect and Reason is the correct explana- tion of the Assertion. (2) Both Assertion and Reason are cor- rect but Reason is not the correct explana- tion of the Assertion. (3) Assertion is cor- rect but Reason is incorrect. (4) Assertion is incor- rect but reason is correct. 36. If the electric flux entering and leaving a closed surface are S.I. units re‐ spectively, then the charge inside the surface of permittivity of free space is (1) (2) (3) (4) 37. A test charge is moved without acceleration from to along the path as shown in figure. The potential difference between and is +2 nC −8 nC d d 2 d 3d 4 4d 3 Q −2Q Q E −2Q − E 2 − 3E 2 −E −2E d F F/3 √3 d 2√3 d 3d 9d m V m m 25 V − m 50 V − m 100 V − m 200 V − m m 0.002 πm +1C 7.5 × 10 7NC −1 7.2 × 10 7NC −1 6.2 × 10 7NC −1 6.5 × 10 7NC −1 +10μC cm cm Nm2C −1 1.88 × 10 5 1.72 × 10 5 1.64 × 10 4 1.32 × 10 6 6 × 10 6 and 9 × 10 6 ε0 ε0 × 10 6 −ε0 × 10 6 −2ε0 × 10 6 3ε0 × 10 6 qo A C ABC A C