JEE MAIN - Physics (2020 - 7th January Morning Slot - No. 14)

Two infinite planes each with uniform surface charge density to are kept in such a way that the angle between them is 30o. The electric field in the region shown between them is given by : JEE Main 2020 (Online) 7th January Morning Slot Physics - Electrostatics Question 164 English
$${\sigma \over {{ \in _0}}}\left[ {\left( {1 + {{\sqrt 3 } \over 2}} \right)\widehat y + {{\widehat x} \over 2}} \right]$$
$${\sigma \over {2{ \in _0}}}\left[ {\left( {1 + \sqrt 3 } \right)\widehat y + {{\widehat x} \over 2}} \right]$$
$${\sigma \over {2{ \in _0}}}\left[ {\left( {1 + \sqrt 3 } \right)\widehat y - {{\widehat x} \over 2}} \right]$$
$${\sigma \over {2{ \in _0}}}\left[ {\left( {1 - {{\sqrt 3 } \over 2}} \right)\widehat y - {{\widehat x} \over 2}} \right]$$

Explanation

JEE Main 2020 (Online) 7th January Morning Slot Physics - Electrostatics Question 164 English Explanation

Electric field due to each sheet is uniform and equal to E = $${\sigma \over {2{\varepsilon _0}}}$$

$$ \therefore $$ Electric field along y direction

= $$\left( {{\sigma \over {2{\varepsilon _0}}} - {\sigma \over {2{\varepsilon _0}}}\sin 60^\circ } \right)\widehat y$$

Also Electric field along x direction

= - $${{\sigma \over {2{\varepsilon _0}}}\cos 60^\circ \widehat x}$$

$$ \therefore $$ Now net electric field between plates

= - $${{\sigma \over {2{\varepsilon _0}}}\cos 60^\circ \widehat x}$$ + $$\left( {{\sigma \over {2{\varepsilon _0}}} - {\sigma \over {2{\varepsilon _0}}}\sin 60^\circ } \right)\widehat y$$

= $${ - {\sigma \over {4{\varepsilon _0}}}\widehat x}$$ + $${\sigma \over {2{\varepsilon _0}}}\left( {1 - {{\sqrt 3 } \over 2}} \right)\widehat y$$

= $${\sigma \over {2{ \in _0}}}\left[ {\left( {1 - {{\sqrt 3 } \over 2}} \right)\widehat y - {{\widehat x} \over 2}} \right]$$

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