Question bank/JEE Main/Physics

JEE MainPhysicsModerateElectrostatics

Consider a sphere of radius R which carries a uniform charge
density
ρ\rho. If a sphere of radiusR2\frac{R}{2}iscarved out of it, as
shown, the

ratio
∣E→AE→B∣\left| \frac{{\overset{\rightarrow}{E}}_{A}}{{\overset{\rightarrow}{E}}_{B}} \right|
of magnitude of electric field of magnitude of electric field

E→A {\overset{\rightarrow}{E}}_{A}\ and E→B{\overset{\rightarrow}{E}}_{B},
respectively, atpoints A and B due to the remaining portion is

Show answer and solution
For a solid sphere
E=ρr3ε0E = \frac{\rho r}{3\varepsilon_{0}}
EA=−ρR2(3ε0)E_{A} = \frac{- \rho R}{2\left( 3\varepsilon_{0} \right)}
∣EA∣=ρR6ε0\left| E_{A} \right| = \frac{\rho R}{6\varepsilon_{0}}
Electric field at point B = E_B = E_1A + E_2A

E_1A = Electric Field Due to solid sphere of radius R at point

B=ρR3ε0B = \frac{\rho R}{3\varepsilon_{0}}
E_2A = Electric Field Due to solid sphere of radius R/2 (which having

charge density -
ρ\rho)=−ρR54ε0= - \frac{\rho R}{54\varepsilon_{0}}

Source: Grass-G / P-22 Physcis Paper 19 Dec Eng..docx

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