Electric Field

Assertion: Due to two point charges electric field and electric potential cannot be zero at some point simultaneously.

Reason: Field is a vector quantity and potential is a scalar quantity.

Two point charges $q$ and $2q$ are placed some distance apart. If the electric field at the location of $q$ be $E$, then that at the location of $2q$ will be

Two equal positive charges $\left(q\right)$ are placed at the vertices $B$ and $C$ of an isosceles triangle of base $a$ and height $h=3\sqrt{3}\frac{a}{2}$, as shown in the adjacent figure. When a charge $q^{\text{'}}$ is placed at $A,$ it is found that at a point inside the triangle, the net electric field due to the three charges vanishes. If this point is at a height $\frac{h}{3},$ then what is $q^{\text{'}}$?

The maximum field intensity on the axis of a uniformly charged ring of charge $q$ and radius $R$ will be

Two large circular discs separated by a distance of $0.01 \mathrm{m}$ are connected to a battery via a switch as shown in the figure. Charged oil drops of density $900 \mathrm{kg}{ \mathrm{m}}^{-3}$ are released through a tiny hole at the center of the top disc. Once some oil drops achieve terminal velocity, the switch is closed to apply a voltage of $200 \mathrm{V}$ across the discs. As a result, an oil drop of radius $8\times {10}^{-7} \mathrm{m}$ stops moving vertically and floats between the discs. The number of electrons present in this oil drop is ______.(neglect the buoyancy force, take acceleration due to gravity $=10{ \mathrm{ms}}^{-2}$ and charge on an electron $\left(\mathrm{e}\right)=1.6\times {10}^{-19}\mathrm{C}$)

Infinite number of charges of magnitude $6 \mu \mathrm{C}$ each are lying at $y=2, 4, 8, 16\dots$ metre on $Y$-axis. The value of electric field intensity at point $y=0$ due to these charges will be $a\times {10}^4 \mathrm{N} {\mathrm{C}}^{-1}$, find the value of $a$,

In Millikan's experiment, static electric charge on the oil drops has been obtained by shining $\mathrm{X}$-rays. If the static electric charge on the oil drop is $-1.282\times {10}^{-18} \mathrm{C}$, calculate the number of electrons present on it.

The tracks of three charged particles in a uniform electrostatic field are shown in the figure. Which particle has the highest charge to mass ratio?

If the flux of the electric field through a closed surface is zero then

The constant $\mathrm{k}$ in Coulomb’s law depends on

A metal plates of capacitor of area $0.01 {\mathrm{m}}^2$ carries a charge of $100 \mathrm{\mu C}$. Calculate the outward pull on plate (in newton).

A metallic shpere is placed in a uniform electric field. The line of force follow the path(s) shown in the figure as,

The maximum field intensity on the axis of a uniformly charged ring of charge $q$ and radius $R$ will be

A thin conducting ring of radius $R$ is given a charge $+Q$. The electric field at the centre $O$ of the ring due to the charge on the part $AKB$ of the ring is $E$. The electric field at the centre due to the charge on the part $ACDB$ of the ring is

The tracks of three charged particles in a uniform electrostatic field are shown in the figure. Which particle has the highest charge to mass ratio?

If the flux of the electric field through a closed surface is zero

An early model of an atom considered it to have a positively charged point nucleus of charge $\mathrm{Z}\mathrm{e}$ surrounded by a uniform density of negative charge upto a radius $\mathrm{R}$ . The atom as a whole is neutral. The electric field at a distance $\mathrm{r}$ from the nucleus is $(\mathrm{r}<\mathrm{R})$

The constant $\mathrm{k}$ in Coulomb’s law depends on

Force acting upon a charged particle kept between the plates of a charged condenser is $F$. If one of the plates of the condenser is removed, force acting on the same particle becomes