1
WB JEE 2021
+1
-0.25
Three infinite plane sheets carrying uniform charge densities $$-$$ $$\sigma$$, 2$$\sigma$$, 4$$\sigma$$ are placed parallel to XZ-plane at Y = a, 3a, 4a respectively. The electric field at the point (0, 2a, 0) is
A
$${{5\sigma } \over {2{\varepsilon _0}}}\widehat j$$
B
$$- {{7\sigma } \over {2{\varepsilon _0}}}\widehat j$$
C
$${\sigma \over {2{\varepsilon _0}}}\widehat j$$
D
$${{5\sigma } \over { - 2{\varepsilon _0}}}\widehat j$$
2
WB JEE 2021
+1
-0.25
Two point charges +q1 and +q2 are placed a finite distance d apart. It is desired to put a third charge q3 in between these two charges, so that q3 is in equilibrium. This is
A
possible only if q3 is negative.
B
possible only if q3 is positive.
C
possible irrespective of the sign of q3.
D
not possible at all.
3
WB JEE 2020
+1
-0.25
As shown in the figure, a point charge q1 = + 1 $$\times$$ 10-6 C is placed at the origin in xy-plane and another point charge q2 = + 3 $$\times$$ 10-6 C is placed at the coordinate (10, 0).

In that case, which of the following graph(s) shows most correctly the electric field vector in Ex in x-direction?
A
B
C
D
4
WB JEE 2020
+1
-0.25
Four identical point masses, each of mass m and carrying charge + q are placed at the corners of a square of sides a on a frictionless plane surface. If the particles are released simultaneously, the kinetic energy of the system when they are infinitely far apart is
A
$${{{q^2}} \over a}(2\sqrt 2 + 1)$$
B
$${{{q^2}} \over a}(\sqrt 2 + 2)$$
C
$${{{q^2}} \over a}(\sqrt 2 + 4)$$
D
$${{{q^2}} \over a}(\sqrt 2 + 1)$$
WB JEE Subjects
Physics
Mechanics
Electricity
Optics
Modern Physics
Chemistry
Physical Chemistry
Inorganic Chemistry
Organic Chemistry
Mathematics
Algebra
Trigonometry
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Calculus
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