Question 1 :
Two identical copper spheres carrying chatges $+Q$ and $-9Q$ separated by a certain distance has attractive force F. If the spheres are allowed to touch eacxh other and moved to distance of separation 'x'. So that the force between them becomes $\cfrac {4F}{9}$. Then x is equal to
Question 2 :
A long string with a charge of $\lambda $ per unit length passes through an imaginary cube of edge length $a$. The maximum flux of the electric field through the cube will be:
Question 3 :
Electric field due to an infinite sheet of charge having surface density $\sigma$ is $E$. Electric field due to an infinite conducting sheet of same surface density of charge is
Question 4 :
A charged oil drop is suspended in uniform field of $3\times 10^4V/m$ so that it neither falls nor rises. The charge on the drop will be: (Take the mass of the charge $=9.9\times 10^{-15}$kg and $g=10m/s^2$)
Question 5 :
Force between two charges $q_1$ and $q_2$ separated by a distance r is proportional to $q _ { 1 } q _ { 2 } / r ^ { 2 }$ . Proportionality constant is
Question 6 :
On the axis and on the equator of an electric dipole for all points _________.
Question 7 :
The electric flux from a cube of edge $l$ is $\phi$. If an edge of the cube is made $2l$ and the charge enclosed is halved, its value will be :
Question 9 :
Assertion: Three equal charges are situated on a circle of radius r such that they form on equilateral triangle, then the electric field intensity at the centre is zero
Reason: The force on unit positive charge at the centre, due to the three equal charges are represented by the three sides of a triangle taken in the same order. Therefore, electric field intensity at centre is zero
Question 10 :
A conducting sphere is negatively charged. Which of the following statements is true?
Question 11 :
According to Gauss' theorem, electric field of an infinitely long straight wire is proportional to
Question 12 :
Given that $q_1 + q_2 = q$. If the force between $q_1$ and $q_2$ is maximum, then $\dfrac{q_1}{q_2}$ is
Question 13 :
A positive charge $Q$ is situated at the centre of a cube. The electric flux through any face of the cube is (in SI units) :
Question 14 :
In a certain region of space, electric field is along z-direction throughout. The magnitude of electric field is, however, not constant but increases uniformly along the positive z-direction, at the rate of $10^5 NC^{-1}$ per metre. What is the torque experienced by a system having a total dipole moment equal to $10^{-7}$ C-m in the negative z-direction?
Question 15 :
Find the magnitude of a charge which produces an electric field of strenght is 18 x $10^3NC^{-1}$ at a distance of 5 m in air.
Question 16 :
A thin rod placed long x-axis from x=-a to x=+a, the rod carries a change uniformly distributed along its length with linear charge density $\lambda$. The potential at the point P (2a, 0, 0) will be
Question 17 :
An electric dipole is placed in an electric field generated by a point charge. Then
Question 18 :
If the flux of the electric field through a closed surface is zero,
Question 19 :
Electric field in a region is given by $E = (2\overrightarrow{i} + 3\overrightarrow{j} - 4\overrightarrow{k})V/m$. Find the potential differences between points $(0, 0, 0)$ and $(1, 2, 3)$ in this region.
Question 20 :
A neutral water molecule $ (H_2 O) $ in its vapour state has an electric dipole moment of $ 2 \times 10^{-24} C-m. $ If the molecule is placed in an electric field of $ 2 \times 10^{4} NC^{_1} $ , the maximum torque that the field can exert on it is nearly.<br><br>
Question 21 :
A total charge of $\displaystyle 5\mu c$ is distributed uniformally on the surface of the thin walled semi spherical cup. If the electric field strength at the center of the semi sphere is $\displaystyle 9\times { 10 }^{ 8 }N{ C }^{ -1 }$, the radius of the cup is:<br/>$\displaystyle \left( \frac { 1 }{ 4\pi { \in  }_{ 0 } } =9\times { 10 }^{ 9 }N{ m }^{ 2 }{ C }^{ -2 } \right) $<br/>
Question 22 :
An electric dipole (dipole moment $=p$) is placed in a uniform electric field in stable equilibrium position at rest. Now it is rotated by a small angle and released. The time after which it comes to the equilibrium position again (for first time) is $t$. Then the moment of inertia of the dipole about the axis of rotation is :
Question 23 :
If the radius of a sphere doubled without changing the charge on it, then electric flux originating form the sphere is:
Question 24 :
There are $4\times { 10 }^{ 23 }$ atoms in a metal sphere. If one electron is removed from $0.1\%$ of atoms, what will be the charge on the sphere?
Question 25 :
The total number of lines of force passing through a surface is called
Question 26 : <p><span class="wysiwyg-font-size-small"><span class="wysiwyg-font-size-small">Three charges each equal to $10^{-9}C$<i> </i><span class="wysiwyg-font-size-small"><span class="wysiwyg-font-size-small">are placed<span class="wysiwyg-font-size-small"><span class="wysiwyg-font-size-small"> at the corners of equilateral triangle of side $1\ m$.<span class="wysiwyg-font-size-small"><span class="wysiwyg-font-size-small"> The force on one of the charges is:</p>
Question 27 :
Two charges of 10 C and -15 C are separated in air by 1m.The ratio of force exerted by one on the other is
Question 28 :
Compare how the magnitude of the electric field decreases with distance from a uniform charged sphere and a uniform charged wire.
Question 29 :
Two particles having charges $q_1$ and $q_2$ when kept at a certain distance, exert a force F on each other. If the distance between the two charges is reduced to half then the force exerted on each other would be:
Question 30 :
A uniform electric field $E=2\times { 10 }^{ 3 }N { C }^{ -1 }$ is acting along the positive x-axis. The flux through the same square if the line normal to tis plane makes a ${ 60 }^{ o }$ angle with the x-axis is
Question 31 :
A dipole is placed in an electric field whose direction is fixed but its magnitude varies with distance. It is possible that the dipole experiences :
Question 32 :
The electric field strength at a distance $r$ from a charge $q$ is $E$. What will be electric field strength if the distance of the observation point is increased to $2r$?
Question 33 :
Two point charges of $+3\mu C$ and $+4\mu C$ repel each other with a force of $10N$. If each is given an additional charge of $-6\mu C$, the new force is:
Question 34 :
Two charges are at a distance $d$ apart. If a copper plate of thickness $d/2$ is kept between them, then effective force will be
Question 36 :
Three charge $q,Q,4q$ are placed in a straight line of length $l$ at points distant $0,\cfrac{l}{2},l$ respectively from one end. In order to make the net force on $q$ zero, the charge $Q$ must be equal to :
Question 37 :
Gaus's law is given by ${ \in  }_{ 0 }\int _{ s }^{  }{ \vec { E } .d\vec { s }  } =q$, if net charge enclosed by a Gassian surface is zero then :
Question 38 :
If the electric field in some region of space is zero,
Question 39 :
A point charge $q = - 8 nC$ is located at the origin. Find the electric field vector at the point $x= 1.2m,  y = -1.6m$ :
Question 40 :
Three charges $+q,+2q$ and $4q$ are placed at point $A(0,0),B(0,a)$ and $C(0,2a)$ and connected by strings. What is ratio of tensions in the strings $AB$and $BC$.
Question 41 :
A rod of length L lies along the x-axis with its left end at the origin. It has a nonuniform charge density $\lambda = \alpha x$, where $\alpha$ is a positive constant. What are the units of $\alpha$?
Question 42 :
Point $P$ lies on the axis of a dipole. If the dipole is rotated by ${ 90 }^{ \circ }$ anticlockwise, the electric field vector $\overrightarrow { E } $ at $P$ will rotate by :<br>
Question 43 :
An $\alpha$ particle is situated in an electric field of strength $15\times {10}^{4}N{C}^{-1}$. Force acting on it is
Question 44 : <p class="wysiwyg-text-align-left">Charges of $40\mu C, -40\mu C$ and$10\mu C$ are placed in air at the corners A, B and C respectively of an equilateral triangle of side $2cm$. The resultant force on the charge at C is :<br/></p>
Question 45 :
Paper snippets attracted by a charged rod is an example of
Question 46 :
$\begin{array} { l } { \text { Four equal charges } Q \text { are placed at the four corners of a square of side a each. Work done i } } \\ { \text { removing a charge } - Q \text { from its centre to infinity is: } } \end{array}$
Question 47 :
The electric field just outside the surface of conductor of area $A$ and surface charge density $\sigma$ is given by
Question 48 :
Let $\displaystyle { E }_{ a }$ be the electric field due to a dipole in its axial plane distant $\displaystyle \ell $ and $\displaystyle { E }_{ q }$ be the field in the equatorial plane distant $\displaystyle { l }^{ 1 }$, then the relation between $\displaystyle { E }_{ a }$ and $\displaystyle { E }_{ q }$ will be :
Question 49 :
A uniform line charge with linear density $\lambda$ lies along the y-axis. What flux crosses a spherical surface centred at he origin with $r\ =\ R$
Question 50 : <span class="wysiwyg-font-size-small"><span class="wysiwyg-font-size-small"><p>A charge of $10$ $units$ is divided so that force between the two charges is maximum when placed $2$ $cm$ apart. The two charges are:<br/></p>
