Tiêu đề 01. ELECTRIC CHARGES AND FIELDS(H).pdf ✅

NEET REVISION 8. A particle having charge that of an electron and mass is projected with an initial speed at an angle to the horizontal from the lower plate of a parallel plate capacitor as shown in the figure. The plates are sufficiently long and have separation 2 . The maximum value of velocity of particle not to hit the upper plate is . Take electric field be‐ tween the plates as directed upward. Find . [Q358199] (1) 8 (2) 10 (3) 15 (4) 16 9. A solid sphere of radius and volume charge density is enclosed by a hollow sphere of radius with negative surface charge density such that the total charge in the system is zero. is a positive constant and is the distance from the centre of the sphere. The ratio is [Q357986] (1) (2) (3) (4) 10. Two charges of and are situated at the points and respectively. The electric flux through a sphere of radius ' ' hav‐ ing center at origin is [Q358331] (1) (2) (3) (4) 11. If a charge is moving along the direction of coulomb’s force of an electric field, [Q358226] (1) Work is done by the electric field (2) Energy is used from some outside source (3) Strength of field decreases (4) Energy of the system is decreased 12. 3 charges are placed as shown in the figure. The net force on charge is: [Q358082] (1) (2) (3) (4) 13. and are two hollow concentric cubes en‐ closing charges and respectively as shown in figure. The ratio of electric flux passing through and is [Q358335] (1) (2) (3) (4) 14. Two small spheres each of mass and with a charge lie inside a nonconducting smooth hemispherical bowl of radius . Find if the equilibrium separation between the two charges is . [Q358054] (1) (2) (3) (4) 15. A particle of mass and charge enters the region between the two charged plates initially moving along -axis with speed as shown in figure. The length of plate is and a uniform electric field is maintained between the plates.The vertical deflection of the particle at the far edge of the plate is [Q358218] (1) (2) (3) (4) 16. A short electric dipole of dipole moment is placed at a distance from the centre of a solid metallic sphere of radius as shown in the figure. The electric field intensity at the cen‐ tre of sphere due to induced charge on the sphere is [Q358172] 1.6 × 10 −30 kg u 45 ∘ cm √W × 10 6 ms −1 10 3V m−1 W R1 ρ = ρ0 r R2 σ, ρ0 r R2/R1 σ/ρ0 ρ0/σ √ρ0/2σ √2σ/ρ0 5Q −2Q (3a, 0) (−5a, 0) 4a 2Q ε0 7Q ε0 5Q ε0 3Q ε0 q 2KQqx 2 (a2 + x2) y 2 2KQqx (a 2 + x 2) 3/2 KQqx (a 2 + x 2) 3/2 3 2 KQqx (a 2 + x 2) 3/2 C1 C2 2 Q 3 Q C1 C2 3 : 2 5 : 2 2 : 5 2 : 3 m q R q d √ 2mgπε0d 3 √R2− d2 4 √ mgπε0d 3 √R2−d 2 √ mgε0d 3 √R2+d 2 √mgε0d3 m −q x vx L E qEL 2 2mv 2 x qEL 2 2mvx 2mv 2 x qEL 2 2mvx qE2L p→ r a (<< r) C
NEET REVISION (1) (2) (3) (4) 17. In a cuboid of dimension , a charge is placed at the center of the surface ' ' having area of . The flux through the oppo‐ site surface to ' ' is given by [Q358334] (1) (2) (3) (4) 18. A simple pendulum has a length and the mass of the bob is . The bob is given a charge coulomb. The pendulum is suspended between the vertical plates of a charged parallel plate ca‐ pacitor. If is the electric field strength between the plates, the time period of the pendulum is given by [Q358202] (1) (2) (3) (4) 19. A particle of charge and mass moves in a circle of radius around an infinitely long line charge of linear density . Then time period will be given as (Consider as Coulomb's con‐ stant) [Q358039] (1) (2) (3) (4) 20. Three small dipoles are arranged as shown be‐ low. What will be the net electric field at [Q358171] (1) (2) (3) (4) Zero 21. A small ball of mass having a charge of is suspended by a string of length . Another identical ball having the same charge is kept at the point of suspension. The minimum horizontal velocity which should be imparted to the lower ball, so that it can make complete revo‐ lution is____ . (Take ) [Q358119] (1) (2) (3) (4) 22. Let be the uniform surface charge density of two infinite thin plane sheets shown in figure. Then the electric fields in three different region and are [Q357954] (1) (2) (3) (4) 23. Two point charges are placed at from the origin on the and axis as shown in the figure. The electric field vector at point ( , ) will sub‐ tend an angle with the - axis given by [Q358193] (1) (2) (3) (4) 24. Positive charge is distributed uniformly over a circular ring of radius . A point particle hav‐ ing a mass (m) and a negative charge is placed on its axis at a distance from the centre. Assuming , find the time period of oscilla‐ tion of the particle, if it is released from there [neglect gravity]. [Q358031] (1) (2) (3) (4) None of these Zero along CO 2kp r 3 along OC 2kp r 3 along CO kp r 3 2L × 2L × L q S 4L 2 S q 12ε0 q 2ε0 q 3ε0 q 6ε0 l m q E 2π√ l g 2π√ l √g+ qE m 2π√ l √g− qE m 2π√ l √g 2+( ) 2 qE m −q m r +λ k T = 2πr√ m 2kλq T = √ 1 2π 2kλq m T 2 = r 3 4π 2m 2kλq T = √ 1 2πr m 2kλq O (k = ) 1 4πε0 8kp x3 kp x3 √2kp x3 10 −3 kg 1 μC 1.0 m m/s √10 = 3.16 3.24 m/s 2.96 m/s 8.35 m/s 6.32 m/s σ EI , EII EIII E→ I = 0, E→ II = n^, E→ III = 0 σ ε0 E→ I = n^, E→ II = 0, E→ III = n^ 2σ ε0 2σ ε0 E→ I = − n^, E→ II = 0, E→ III = n^ σ ε0 σ ε0 E→ I = n^, E→ II = 0, E→ III = n^ σ 2ε0 σ 2ε0 q1 = 2μC and q2 = 2μC b = 1 cm and a = 2 cm y x a b θ x tan θ = 1 tan θ = 4 tan θ = 2 tan θ = 3 Q R q x x < R [ ] 1/2 16π 3ε0R 3m Qq [ ] 1/2 8π 2ε0R 3 q [ ] 1/2 2π 2ε0R3 3q
NEET REVISION 25. An electric field is given by, . The electric flux through a surface area lying in plane (in unit) is [Q358284] (1) 150 (2) 60 (3) 180 (4) 90 26. Two identical conducting balls and have positive charges and respectively but . The balls are brought together so that they touch each other and then kept in their orig‐ inal positions. The force between them is [Q358093] (1) less than that before the balls touched (2) greater than that be- fore the balls touched (3) same as that before the balls touched (4) zero 27. A charge is uniformly distributed in a hollow sphere of radii and . The electric field at a point distance from the centre for is [Q358003] (1) (2) (3) (4) 28. The electric field in a region is The charge contained inside a cubical volume bounded by the surfaces is (where , , are in ) [Q358289] (1) (2) (3) (4) 29. Two charges and are present as shown.Two dielectrics of thickness and and dielectric constants and are introduced as shown. Find the force between the charges [Q358081] (1) (2) (3) (4) Zero 30. An electric dipole is placed along the -axis at the origin . A point is at a distance of 10 from this origin such that makes an angle with -axis. If the electric field at makes an angle with the -axis, the value of would be [Q358149] (1) (2) (3) (4) 31. Three small dipoles are arranged as shown be‐ low. What will be the net electric field at point [Q358169] (1) (2) (3) (4) 32. Force between two point charges and placed in vacuum at ' ' apart is . Force be‐ tween them when placed in a medium having di‐ electric constant at ' ' apart will be [Q358088] (1) (2) (3) (4) 33. Two small spheres of masses are suspended by weightless insulating threads of lengths . The spheres carry charges respectively. The spheres are sus‐ pended such that they are in level with one an‐ other and the threads are inclined to the vertical at angles of as shown in figure. Which one of the following conditions is essential, if [Q358052] (1) (2) (3) (4) 34. In the figure, a cone of radius is shown. Electric field of intensity is present perpen‐ dicular to the circular cross-section of the cone. The electric flux through the carved surface of the hemisphere is [Q358333] (6^i + 5^j + 3k^)N/C 30 ^i m2 Y Z− SI A B q1 q2 q1 ≠ q2 Q r1 r2(r2 > r1) P x r1 < x < r2 Q(x) 4πε0(r 3 2−r 3 1 ) Q(x 3−r 3 1 ) 4πε0(r 3 2−r 3 1 ) Q(x 3−r 3 1 ) 4πε0x2(r 3 2−r 3 1 ) Qr 3 1 4πε3x2(r 3 3−r 3 1 ) E = ˆi 5×10 3(NC−1cm−1)x 2 x = 0, x = 2, y = 0, y = 2, z = 0, z = 2 x y z cm 1.76 × 10 −11C 3.52 × 10 −11C 2.21 × 10 −8C 2 × 10 −10C Q1 Q2 t1 t2 k1 k2 Q1Q2 4πε0[d+√k1t1+√k2t2] 2 Q1Q2 4πε0 [d−(t1+t2)+k1 t1+k2 t2 ] 2 Q1Q2 4πε0[d−(t1+t2)+√k1 t1+√k2 t2] 2 x O P cm OP π 6 x P β x β π 6 + tan −1 ( ) π 6 1 2√3 2π 6 tan −1 ( ) 1 2√3 O (k = ) 1 4πε0 √5 kp x3 2√5 kp x3 5kp x3 0 q1 q2 r cm F k = 5 r/5 cm 25F F/5 5F F/25 M1 and M2 L1 andL2 Q1 and Q2 θ1 and θ2 θ1 = θ2? M1 ≠ M2 but Q1 = Q2 M1 = M2 Q1 = Q2 L1 = L2 R E0