Question 84 of 311

As shown in the figure, a point charge $Q$ is placed at the centre of conducting spherical shell of inner radius $a$ and outer radius $b$. The electric field due to charge $Q$ in three different regions $I,II\text{and}III$ is given by : $(I:r\lt a,II:a\lt r\lt b,III:r\gt b)$

A${E}_{I}=0,{E}_{II}=0,{E}_{III}\neq 0$B${E}_{I}\neq 0,{E}_{II}=0,{E}_{III}\neq 0$C${E}_{I}\neq 0,{E}_{II}=0,{E}_{III}=0$D${E}_{I}=0,{E}_{II}=0,{E}_{III}=0$

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Answer: (B) ${E}_{I}\neq 0,{E}_{II}=0,{E}_{III}\neq 0$

In region I, due to charge at centre, electric field will be present.
But in region II, electric field will be zero as electric field inside material of conductor is zero.
Again for outside region, net charges enclosed is not zero and therefore electric field will exist.