Electrostatics-10 Important basic MCQs (Quiz) Part 2
1.ABC is a right angled triangle in which AB= 3 cm and BC = 4cm . And \angle ABC\;=\frac{\mathrm\pi}2 . The three charges +15, +12 and -20 e.s.u. are placed respectively on A, B and C . The force acting on B is
(A) 125 dyne
(B) 35 dynes
(C) 25 dynes
(D) Zero
2.Electric charges of 1\mu C, -1\mu C and 2\mu C are placed in air at the corners A, B and C respectively of an equilateral triangle ABC having length of each side 10 cm. The resultant force on the charge at C is
(A) 0.9 N
(B) 1.8 N
(C) 2.7 N
(D) 3.6 N
3. Two charges placed in air repel each other by a force of 10^{-4} N . When oil is introduced between the charges, the force becomes 2.5\;\times\;10^{-5}\;N.The dielectric constant of oil is
(A) 2.5
B) 0.25
(C) 2.0
(D) 4.0
4. Two spherical conductors B and C having equal radii and carrying equal charges in them repel each other with a force F when kept apart at some distance. A third spherical conductor having same radius as that of B but uncharged is brought in contact with B, then brought in contact with C and finally removed away from both. The new force of repulsion between B and C is
(A) F/4
(B) 3F/4
(C) F/8
(D) 3F/8
5. The charges on two sphere are +7µC and –5µC They experience a force F. If each of them is given and additional charge of – 2µC, the new force of attraction will be
(A) F
(B) F / 2
(C) \frac F{\sqrt3}
(D) 2F
6. Electric lines of force about negative point charge are
(A) Circular, anticlockwise
(B) Circular, clockwise
(C) Radial, inward
(D) Radial, outward
7. A charge q is placed at the centre of the line joining two equal charges Q. The system of the three charges will be equilibrium, if is equal to
(A) -\frac Q2
(B)-\frac Q4
(C) +\frac Q4
(D) +\frac Q2
8. ABC is an equilateral triangle. Charges +q are placed at each corner. The electric intensity at O will be
(A)\frac1{4\mathrm\pi\;\in_{\mathrm o}}\frac q{r^2}
(B)\frac1{4\mathrm\pi\;\in_{\mathrm o}}\frac{3q}{r^2}
(C) Zero
(D)\frac1{4\mathrm\pi\;\in_{\mathrm o}}\frac qr
9. The electric field inside a spherical shell of uniform surface charge density is
(A) Zero
(B) Constant, less than zero
(C) Directly proportional to the distance from the centre
(D) None of the above
10.When a body is earth connected, electrons from the earth flow into the body. This means the body is…..
(A) Unchanged
(B) Charged positively
(C) Charged negatively
(D) An insulator
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