1
JEE Main 2014 (Offline)
+4
-1
Assume that an electric field $$\overrightarrow E = 30{x^2}\widehat i$$ exists in space. Then the potential difference $${V_A} - {V_O},$$ where $${V_O}$$ is the potential at the origin and $${V_A}$$ the potential at $$x=2$$ $$m$$ is :
A
$$120$$ $$J/C$$
B
$$-120$$ $$J/C$$
C
$$-80$$ $$J/C$$
D
$$80$$ $$J/C$$
2
JEE Main 2013 (Offline)
+4
-1
Two charges, each equals to $$q,$$ are kept at $$x=-a$$ and $$x=a$$ on the $$x$$-axis. A particle of mass $$m$$ and charge $${q_0} = {q \over 2}$$ is placed at the origin. If charge $${q_0}$$ is given a small displacement $$\left( {y < < a} \right)$$ along the $$y$$-axis, the net force acting on the particle is proportional to
A
$$y$$
B
$$-y$$
C
$${1 \over y}$$
D
$$-{1 \over y}$$
3
JEE Main 2013 (Offline)
+4
-1
A charge $$Q$$ is uniformly distributed over a long rod $$AB$$ of length $$L$$ as shown in the figure. The electric potential at the point $$O$$ lying at distance $$L$$ from the end $$A$$ is
A
$${Q \over {8\pi {\varepsilon _0}L}}$$
B
$${{3Q} \over {4\pi {\varepsilon _0}L}}$$
C
$${Q \over {4\pi {\varepsilon _0}L\,\ln \,2}}$$
D
$${{Q\ln \,2} \over {4\pi {\varepsilon _0}L\,{}^s}}$$
4
AIEEE 2012
+4
-1
This question has statement- $$1$$ and statement- $$2.$$ Of the four choices given after the statements, choose the one that best describe the two statements.
An insulating solid sphere of radius $$R$$ has a uniformly positive charge density $$\rho$$. As a result of this uniform charge distribution there is a finite value of electric potential at the center of the sphere, at the surface of the sphere and also at a point out side the sphere. The electric potential at infinite is zero.

Statement- $$1:$$ When a charge $$q$$ is take from the centre of the surface of the sphere its potential energy changes by $${{q\rho } \over {3{\varepsilon _0}}}$$
Statement- $$2:$$ The electric field at a distance $$r\left( {r < R} \right)$$ from the center of the sphere is $${{\rho r} \over {3{\varepsilon _0}}}.$$

A
Statement- $$1$$ is true, Statement- $$2$$ is true; Statement- $$2$$ is not the correct explanation of Statement- $$1$$.
B
Statement $$1$$ is true, Statement $$2$$ is false.
C
Statement $$1$$ is false, Statement $$2$$ is true.
D
Statement- $$1$$ is true, Statement- $$2$$ is true; Statement- $$2$$ is the correct explanation of Statement- $$1$$.
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