List of practice Questions

A pendulum bob of mass $m$ carrying a charge $q$ is at rest with its string making an angle $\theta$ with the vertical in a uniform horizontal electric field $E$. The tension in the string is

Figure below show regular haxagons, with charges at the vertices. In which case is the electric field at the centre zero ?

Four charges are arranged at the corners of a square as shown in the figure. The direction of electric field at the centre of the square is along

Gausss law is valid for

The reiation between electric field vector E, the displacement vector D and the polarization vector P for a dielectric placed in electric field E is given by

The surface charge density (in $ Cm^{-2} $ ) of the earth is about

Under the influence of the coulomb field of charge $+\,Q$, a charge $-\,q$ is moving around it in an elliptical orbit. Find out the correct statement(s).

For real $x,$ let $f (x) = x^3 + 5x + 1,$ then

A capillary tube of radius r is immersed in water and water rises in it to a height H. Mass of water in the capillary tube is m. If the capillary of radius 2r is taken and dipped in water, the mass of water that will rise in the capillary tube will be

The excess pressure inside a cylindrical drop of liquid or a cylindrical bubble of radius $r$ in a liquid of surface tension $T$ is

The excess pressure inside a spherical drop of water is four times that of another drop. Then their respective mass ratio is

The length of a needle floating on water is 2.5 cm. Calculate the added force (due to surface tension) required to pull the needle out of water. (Surface tension of water $ =7.2\times {{10}^{-2}}N/{{m}^{2}} $ )

Let $A$ be a $2 \times 2$ matrix Statement-1 : adj (adj A) $= A$ Statement-2 : $|adj \,A| = |A|$

A parallel plate air capacitor has a capacitance $C$. When it is half filled with a dielectric of dielectric constant $5$, the percentage increase in the capacitance will be :

The electric potential at a point $(x. y, z)$ is given by $ V = - x^2 y - xz^2 + 4 $ The electric field at that point is

The equivalent capacitance of the circuit will be

Three point charges $ q,\,-2q $ and $ -2q $ are placed at the vertices of an equilateral triangle of side $ a $ . The work done by some external force to increase their separation to $ 2a $ will be

Two charged spheres of radii $R_1 \, and \, R_2$ have equal surface charge density. The ratio of their potential is

Two points $P$ and $Q$ are maintained at the potentials of $10\,V$ and $-4\,V$ respectively. The work done in moving $100$ electrons from $P$ to $Q$ is

Two spherical conductors $B$ and $C$ having equal radii and carrying equal charges in them repel each other with a force $F$ when kept apart at some distance. A third spherical conductor having same radius as that of $B$ but uncharged, is brought in contact with $B$, then brought in contact with $C$ and finally removed away from both. The new force of repulsion between $B$ and $C$ is

What is the energy stored in the capacitor between terminals a and b of the network shown in the figure? (Capacitance of each capacitor C = 1 ??)

$2$-Phenylethylbromide when heated with $NaOEt$, elimination takes place. No deuterium exchange takes place when the reaction is carried out in $C_2H_5OD$ solvent. The mechanism will be

A metal nitrate reacts with $KI$ to give black precipitate which turns to orange on addition of $ KI $ . Metal is

Arrange the carbanions, $\left(CH_{3}\right)_{3}\, \bar{C}, \bar{C}Cl_{3}, \left(CH_{3}\right)_{2}\, \bar{C}H, C_{6}H_{5}\, \bar{C}H_{2}$, in order of their decreasing stability :

Electromeric effect is brought into play only at the requirement of the reagent. It is a temporary effect in which bond pair is shifted to one of the constituent atoms.