Physics-DPP-2-Electrostatics

PHYSICS Topic: ELECTROSTATICS Date: 1. A pendulum bob of mass m carrying a charge q is at rest with its string making an angle  with the vertical in a uniform horizontal electric field E. The tension in the string is mg qE qE (a) sin θ (b) mg (c) sin θ (d) cosθ 2. In a region of space, the electric field is in the x direction and is given as E  E0 x ˆi . Consider an imaginary cubical volume of edge a, with its edges parallel to the axes of coordinates. The charge inside this volume is: (a) zero (b)  E a3 (c) 1 E a3 (d) 1 ε E a2 0 0 0 0 6 0 0 3. Five identical charges each of magnitude q are placed at the five corners of a regular hexagon of side a. the field at the centre of the hexagon is kq (a) a2 (b) (b) 5kq a2 6kq (c) 5a2 5kq (d) 6a2 4. A semicircular ring of radius R is uniformly charged with a charge density . The electric field intensity at the centre of curvature of this ring is λ (a) π Î R λ (b) 2π Î R λ (c) 4π Î R λ (d) 8π Î R 5. A neutral pendulum oscillates in an uniform electric field as shown in figure. If a positive charge is given to the pendulum then its time period (a) will increase (b) will decrease (c) will remain constant (d) will first increase then decrease 6. The figures shows four situations in which charged particles are at equal distances from the origin. If E1, E2, E3 and E4 be the magnitude of the net electric fields at the origin in four situations (i), (ii), (iii) and (iv) respectively, then (i) (ii) (iii) (iv) (a) E1 = E2 = E3 = E4 (b) E1 = E2 > E3 = E4 (c) E1 < E2 < E3 = E4 (d) E1 > E2 = E3 < E4 7. A soap bubble is given a negative charge, then its radius : (a) decreases (b) increases (c) remains unchanged (d) nothing can be predicted as information is insufficient PHYSICS Topic: ELECTROSTATICS Date: 8. There are two metallic spheres of same radii but one is solid and the other is hollow, then : (a) solid sphere can be given more charge (b) hollow sphere can be given more charge (c) they can be charged equally (maximum) (d) none of the above 9. Two similar small spheres having +q and –q charge are kept at a certain distance. F force acts between the two. If in the middle of two spheres, another similar small sphere having +q charge is kept, then it will experience a fource in magnitude and direction as : (a) zero having no direction (b) 8F towards +q charge (c) 8F towards –q charge (d) 4F towards +q charge 10. Two charged spheres separated at a distance d exert a force F on each other. If they are immersed in a liquid of dielectric constant 2, then what is the force (if all conditions are same) : F (a) 2 (b) F (c) 2F (d) 4F PHYSICS Topic: ELECTROSTATICS Date: 1. (c) 2. (b) Answer Key 3. (a) 4. (b) 5. (a) 6. (a) 7. (b) 8. (c) 9. (c) 10. (a)