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Test:— Chapter 2 : Electric Flux, , Maximum Marks: 50, , Duration: 60 minutes, Note: Each Question contains equal Marks, i.e., 2., , Q.1 The surface considered for Gauss's law is called, (a) Closed surface, , (b) Spherical surface, , (c) Gaussian surface, , (d) Plane surface, , Q.2 The total flux through the faces of the cube with side of length a if a charge q is placed at, corner A of the cube is, , +, | x, , £ -t., taf ot, “3, ee, , Q.3 Which of the following statements is not true about Gauss's law?, , (a) Gauss's law is true for any closed surface., , (b) The term q on the right side side of Gauss’s law includes the sum of all charges enclosed by, the surface., , (c) Gauss's law is not much useful in calculating electrostatic field when the system has some, symmetry., , (d) Gauss's law is based on the inverse square dependence on distance contained in the, coulomb's law., , Q.4 The dielectric constant of a metal is:, (a) 0, , (b) 1, , (=, , (d)-1
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Q.5 When a dipole of moment p is placed in uniform electric field E , then the torque acting on, the dipole is:, , (at =p, , (be)? =P +E, , (jt =p+E, , (d)t =p -E, , Q.6 The ratio of electric force between two electrons to the gravitational force between them is, of the order:, , (a) 10%, , (b) 10°, , (c) 10”, , (d)1, , Q.7 Gauss's law will be invalid if, , (a) there is magnetic monopoles., , (b) the inverse square law is not exactly true., , (c) the velocity of light is not a universal constant., (d) none of these., , Q.8 If electric flux through a closed surface is zero. It means that:, (a) the net charge inside the surface is zero., , (b) the electric field is necessarily zero at all points on the surface., (c) no charge exists inside the surface., , (d) no charge exists outside the surface., , QQ Static electricity is produced by, (a) induction only, , (b) friction, , (c) chemical reaction only, , (d) friction and induction both., , Q.10 An electric dipole of moment p is placed in the position of stable equilibrium in a uniform, electric field E . The couple required to rotate it through an angle 6 the initial position is:, , (a) -PE cos 8, , (b) PE tan6, , (c) PE cos 8, , (d) PE sin 6.
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Q.11 Two point charges each of 20 uC are placed 50 cm apart in air. What is the electric field, intensity at the mid point on the line joining the centre of two point charges?, , (a) 5 « 10° NC*, , (b) 18 x 10° NC*, , (c) Zero, , (d) None of these, , Q.12 The surface charge density oil the copper sphere is o. The electric field strength on the, surface of Sphere of radius r is:, , (a) of2, , (b) o, , (c) o/2e0, , (d) o/e0, , Q.13 An electron and a proton are placed in the same uniform electric field. What will be the, ratio of the acceleration of electron to that of proton?, , (a}1, , (b) zero, , (c) m/m,, , (d) mim,, , Q.14 The position of the charge inside the enclosing surface is changed in such a way that the, total charge remains constant. Then the total normal electric flux through the enclosing surface:, (a) increases, , (b) decreases, , (c) changes erratically, , (d) Remains unchanged., , Q.15 .................. iS a central force in nature., (a) Electromagnetic, , (b) Electrodynamic, , (c) Electrostatic, , (d) None of these, , Q.16 Total electric flux coming out of a unit positive charge kept in air is, , (0) & Or", (e) (4x5, (dh 4ea,
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Q.17 An electric charge q is placed at the centre of a cube of side a. The electric flux on one of, its faces will be, (e) ~ o —, , 4, a, , , , o—,, , Q.18 Total electric flux coming out of a unit positive charge kept in air is, , pose ciange weps i aie 1s, sy g", fe) (4ney" (A) ane,, , Q.19 A point charge q is placed at a distance a/2 directly above the centre of a square of side a., The electric flux through the square is, , (a) 9s, () gine,, (©) ge, () ge,, , Q.20 Which of the following statement is correct? Superposition principle stated that—, , (a) Sum of all forces., , (b) Net force experienced by any charge in a group of charges is the vector sum of the forces, acting on it due to rest of the charges of the group., , (c) Integrated sum of any forces., , (d) All of the above., , Q.21 Which of the following is the S.t unit of electric flux—, (a) Farad, , (b) NC“! m?, , (c) C*N* m?, , (d) C?N' m?, , Q.22 What is a Gaussian surface?, , (a) Spherical surface contains a charge q., , (b) an imaginary closed surface in three dimensional space through with the flux of a vector field, is calculated., , (c) An imaginary closed surface in two dimensional space through with flux lines passed out., , (d) b and c both.
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Q.23 Two charges of magnitudes -2 Q and + Q are located at points (a, 0) and (4a, 0), respectively. What is the electric flux due to these charges through a sphere of radius 3a with its, centre at the origin?, , (a) -Qle, , (b) -20/e, , (c) -Qi2e, , (d) Qe, , Q.24 A large plane charge sheet having surface charge density 0 = 2.0 x 10 ~° C m “lies in the, x-y plane. Find the flux of the electric field through a circular area of radius 1 cm lying, completely in the region where x, y, 2 are all positive and with its normal making an angle of 60°, with the z-axis., , (a) 17.5Nm?C~*., , (b) 12. 5Nm?C~*., , (c) 17.0NmC™., , (d)ONm, , Q.25 Acharge of 4 x 10 -° C is distributed uniformly on the surface of a sphere of radius 1 cm. It, is covered by a concentric, hollow conducting sphere of radius 5 cm. (i) Find the electric field at, a point 2 cm away from the centre. (ii) A charge of 6 x 10 -* C is placed on the hollow sphere., Find the surface charge density on the outer surface of the hollow sphere., , (Select the Answer (i) and (ii) respectively.), , (a) (i) 9 * 10°NIC , (il) 10°C, , (b) (i) 5 * 10°NIC , (i) 10*C, , (c) (i) 9x 10° NIC , (il) 10°C, , (d) (i) 2.4 10°NIC, (ii) 107C, , NOTE: THIS IS BASED ON CLASS 12TH SYLLABUS PRESCRIBED, BY NCERT.
