(Solved): Question 7 (a) An infinite sheet carries a uniform surface charge density \( \sigma>0 \). Consider ...

Question 7 (a) An infinite sheet carries a uniform surface charge density \( \sigma>0 \). Consider the point \( P \) at a distance \( r \) above the sheet. By what factor would the electric field at point \( P \) get weaker if a circular section with radius \( r \) was removed from the sheet, beneath point P? (b) Consider a thin, uniformly charged spherical shell with radius \( \mathrm{r} \), carrying a positive charge of Q. A small hole is created, removing \( 0.02 \% \) of the shell, so that a measurement probe can be inserted. What will the measured magnitude and direction of the field be at the centre of the shell?