# 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 –5µ*C* 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) 2*F*

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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