Tiêu đề ELECTRIC CHARGES AND FIELDS.docx.pdf ✅

1.ELECTRIC CHARGES AND FIELDS Single Correct Answer Type 1. A polythene piece, rubbed with wool, is found to have negative charge of 4×10 C. the number of electrons −7 transferred from wool to polythene is a) 1. 5×10 12 b) 2. 5×10 12 c) 2. 5×10 13 d) 3. 5×10 13 2. The intensity of electric field at a point between the plates of a charged capacitor a) Is directly proportional to the distance between the plates b) Is inversely proportional to the distance between the plates c) Is inversely proportional to the square of the distance between the plates d) Does not depend upon the distance between the plates 3. Four metal conductors having different shapes I. A sphere II. Cylinder III. Pear IV. Lightning conductor are mounted on insulating stands and charged. The one which is best suited to retain the charges for a longer time is a) 1 b) 2 c) 3 d) 4 4. Three charges –q and are placed as shown in figure. The component of the force on is 1 , + q 2 − q 3 x –q 1 proportional to a) sinθ q 2 b 2 − q 3 b 2 b) cos θ q 2 b 2 − q 3 b 2 c) sinθ q 2 b 2 + q 3 b 2 d) cos θ q 2 b 2 + q 3 b 2 5. According to Gauss’ Theorem, electric field of an infinitely long straight wire is proportional to a) r b) 1/r 2 c) 1/r 3 d) 1/r 6. An electric dipole has a pair of equal and opposite point charges q and –q separated by a distance2x. The axis of the dipole is defined as a) Direction from positive charge to negative charge b) Direction from negative charge to positive charge c) Perpendicular to the line joining the two charges drawn at the centre and pointing upward direction d) Perpendicular to the line joining the two charges drawn at the centre and pointing downward direction 7. The Gaussian surface for calculating the electric field due to a charge distribution is Page| 1
a) Any surface near the charge distribution b) Always a spherical surface c) A symmetrical closed surface containing the charge distribution, at every point of which electric field has a single fixed value d) None of the given options 8. Two charged spheres of radii 10 cm and 15 cm are connected by a thin wire. No charge will flow, if they have a) The same charge on each b) The same potential c) The same energy d) The same field on their surface 9. Three charges each of + 1μCare placed at the corners of an equilateral triangle. If the force between any two charges be F, then the net force on either charge will be a) 2 F b) F 3 c) 2F d) 3F 10. The work done in carrying a charge of 5μC from a point A to a point B in an electric field is 10mJ. The potential difference (V is then B − V A ) a) + 2kV b) − 2 kV c) + 200 V d) − 200 V 11. A parallel plate condenser has a uniform electric field E(V/m) in the space between the plates. If the distance between the plates is d(m) and area of each plate is A(m the energy (joules) stored in the 2 ) condenser is a) 1 2 ε 0 E 2Ad b) E 2Ad/ε 0 c) 1 2 ε 0 E 2 d) ε 0 EAd 12. Two capacitors each of 1μF capacitance are connected in parallel and are then charged by 200 volts d. c. supply. The total energy of their charges (in joules) is a) 0.01 b) 0.02 c) 0.04 d) 0.06 13. Identify the wrong statement in the following. Coulomb’s law correctly described the electric force that a) binds the electrons of an atom to its nucleus b) binds the protons and neutrons in the nucleus of an atom c) binds atoms together to form molecules d) Binds atoms and molecules to from solids 14. When one electron is taken towards the other electron, then the electric potential energy of the system a) Decreases b) Increases c) Remains unchanged d) Becomes zero 15. All capacitors used in the diagram are identical and each is of capacitance C. Then the effective capacitance between the points A and B is a) 1. 5C b) 6C c) C d) 3C Page| 2