Magnetic Field and Flux Density

hi
1. Which of these is not correct as a basic property of electric charges?
(a) Total charges in an insulated system is invariable
(b) A charged body is electrically unstable
(c) * A charged body has equal number of positive and negative charges
(d) Positively charged body is deficient of electrons

x+q1+q2 = 2 q1

2.Calculate the distance x between charges q1 and q2 shown, given the repulsive force between them as 1.2 x 10-4 N, take the permittivity of vacuum where they were as 8.842x 10 -12 F/M and charge on q1=
1.6x10-19c
(a) * 1.96x10-12M (b) 9.1x104N (c) 16.8x10-4 N. (d) 4.3x108 N

3. Two charges separated by distance x are located in vacuum.
One is a quarter in a magnitude of the other. In terms of two charges above Coulomb’s law can correctly represented by:
(a) (b) (c) * (d)

4. Find the ratio (Fe/Fg) of the Coulomb electrical force Fe, to the gravitational force, Fg, between two electrons separated by distance r
(a)*4.2* (b) (c) (d)

5. Two identical balls, carrying equal charge each of mass
0.10g, are suspended freely by two threads of equal length repelled each other so that each thread make angle 300 with vertical line. At equilibrium, calculate the tension in one of the threads.
(Acceleration of gravity pull g = 9.8 m/s2)
(a)* 1.13x10-3 N (b) 6.3x10-6 N (c) 0.41 N (d) 5.1 x10-12 N

6. When two identically charged bodies suspended freely by thread of equal length repel each other all of these forces are acting on one of then except:

(a) Tension (b) Gravitational pull (c)* Coulomb attraction force (d)
Repulsive force

D

E

A

C

B

+3mC

-5mC

7. Two charges are separated as shown. Where a third positive charge must be placed if the force it experiences is to be zero?

(a)* At D (b) At C (c) At E (d) At B

8. For series of charges in a closed