WB JEE 2021 | Electrostatics Question 17 | Physics

The variation of electric field along the Z-axis due to a uniformly charged circular ring of radius a in XY-plane as shown in the figure. The value of coordinate M will be

$${1 \over 2}$$

$$\sqrt 2 $$

$${1 \over {\sqrt 2 }}$$

WB JEE 2021

MCQ (Single Correct Answer)

-0.25

A metal sphere of radius R carrying charge q is surrounded by a thick concentric metal shell of inner and outer radii a and b, respectively. The net charge on the shell is zero. The potential at the centre of the sphere, when the outer surface of the shell is grounded will be

$${q \over {4\pi {\varepsilon _0}}}\left( {{1 \over a} - {1 \over b}} \right)$$

$${q \over {4\pi {\varepsilon _0}}} - {1 \over a}$$

$${q \over {4\pi {\varepsilon _0}}}\left( {{1 \over R} - {1 \over a}} \right)$$

$${q \over {4\pi {\varepsilon _0}}} - {1 \over R}$$

WB JEE 2021

MCQ (Single Correct Answer)

-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

$${{5\sigma } \over {2{\varepsilon _0}}}\widehat j$$

$$ - {{7\sigma } \over {2{\varepsilon _0}}}\widehat j$$

$${\sigma \over {2{\varepsilon _0}}}\widehat j$$

$${{5\sigma } \over { - 2{\varepsilon _0}}}\widehat j$$

WB JEE 2021

MCQ (Single Correct Answer)

-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

possible only if q₃ is negative.

possible only if q₃ is positive.

possible irrespective of the sign of q₃.

not possible at all.

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