There are two charges $+1$ microcoulombs and $+5$ microcoulombs. The ratio of the forces acting on them will be

A conducting sphere of radius $R$, and carrying a charge $q$ is joined to a conducting sphere of radius $2R$, and carrying a charge $-2q$. The charge flowing between them will be

Four charges are placed at the circumference of the dial of a clock as shown in figure. If the clock has only hour hand, then the resultant force on a positive charge $q_0$ placed at the centre, points in the direction which shows the time as 

Two positive point charges of unequal magnitude are placed at a certain distance apart. A small positive test charge is placed at null point, then

Positive charge $Q$ is distributed uniformly over a circular ring of radius $R$. A point particle having a mass $(m)$ and a negative charge $-q$ is placed on its axis at a distance $x$ from the centre. Assuming $x < R,$ find the time period of oscillation of the particle, if it is released from there [neglect gravity].

The magnitude of electric force on $2\, \mu \,C$ charge placed at the centre $O$ of two  equilateral triangles each of side $10 \,cm$, as shown in figure is $P$. If charge $A, B, C, D, E$ and $F$ are $2\, \mu \,C, 2\, \mu \,C, 2\, \mu \,C,-2\, \mu \,C, -2\, \mu \,C, -2\, \mu \,C$   respectively, then $P$ is :.....$N$