Two charges $\pm 10\; \mu C$ are placed $5.0\; mm$ apart. Determine the electric field at $(a)$ a point $P$ on the axis of the dipole $15 cm$ away from its centre $O$ on the side of the positive charge, as shown in Figure $(a),$ and $(b)$ a point $Q , 15\; cm$ away from $O$ on a line passing through $O$ and normal to the axis of the dipole, as shown in Figure.

How many electrons should be removed from a coin of mas $1.6 \,g$, so that it may float in an electric field of intensity $10^9 \,N / C$ directed upward?

The distance between a proton and electron both having a charge $1.6 \times {10^{ – 19}}\,coulomb$, of a hydrogen atom is ${10^{ – 10}}\,metre$. The value of intensity of electric field produced on electron due to proton will be

Two charges $+Q$ and $-2 Q$ are located at points $A$ and $B$ on a horizontal line as shown below.The electric field is zero at a point which is located at a finite distance

Two point charges $q_{ A }=3\; \mu \,C$ and $q_{ B }=-3\; \mu \,C$ are located $20\; cm$ apart in vacuum.

$(a)$ What is the electric field at the midpoint $O$ of the line $AB$ joining the two charges?

$(b)$ If a negative test charge of magnitude $1.5 \times 10^{-9}\; C$ is placed at this point, what is the force experienced by the test charge?