Q.

A thin infinite sheet charge and an infinite line charge of respective charge densities +σ and +λ are placed parallel at 5 m distance from each other. Points 'P' and 'Q' are at 3π m and 4π m perpendicular distance from the line charge towards the sheet charge, respectively. 'EP' and 'EQ' are the magnitudes of resultant electric field intensities at point 'P' and 'Q', respectively. If EPEQ=4a for 2|σ|=|λ|, then the value of a is ________.               [2023]


Ans.

(6)

EA=λ2πε0rA-σ2ε0{rA=3π}=12ε0[λ3-σ]

EB=λ2πε0rB-σ2ε0{rB=4π}=12ε0[λ4-σ]

EAEB=43(λ-3σλ-4σ)=43[2σ-3σ2σ-4σ]=43[-σ-2σ]=46