List of top Physics Questions on Electric Charge asked in AIEEE

A thin semi-circular ring of radius $r$ has a positive charge $q$ distributed uniformly over it. The net field $\vec{E}$ at the centre $O$ is

A charge $Q$ is placed at each of the opposite corners of a square. A charge $q$ is placed at each of the other two corners. If the net electrical force on $Q$ is zero, then the $Q/q $ equals

A charged ball $B$ hangs from a silk thread $S$, which makes an angle $\theta$ with a large charged conducting sheet $P$, as shown in the figure. The surface charge density $\sigma$ of the sheet is proportional to:

A charged oil drop is suspended in a uniform field of $3 ? 10^4 \,V/m$ so that it neither falls nor rises. The charge on the drop will be (take the mass of the charge $= 9.9 ? 10^{-15}\, kg$ and $g = 10\, m/s^2$)