31. A spherical metal shell $A$ of radius $R _ { A }$ and a solid metal sphere $B$ of radius $R _ { B } \left( < R _ { A } \right)$ are kept far apart and each is given charge ' $+ Q$ '. Now they are connected by a thin metal wire. Then\\
(A) $\quad E _ { A } ^ { \text {mide } } = 0$\\
(B) $Q _ { A } > Q _ { B }$\\
(C) $\frac { \sigma _ { A } } { \sigma _ { B } } = \frac { R _ { B } } { R _ { A } }$\\
(D) $E _ { A } ^ { \text {on surface } } < E _ { B } ^ { \text {on surface } }$

\section*{ANSWER: ABCD}
\begin{enumerate}
  \setcounter{enumi}{31}
  \item An electron and a proton are moving on straight parallel paths with same velocity. They enter a semi-infinite region of uniform magnetic field perpendicular to the velocity. Which of the following statement(s) is/are true?\\
(A) They will never come out of the magnetic field region.\\
(B) They will come out travelling along parallel paths.\\
(C) They will come out at the same time.\\
(D) They will come out at different times.
\end{enumerate}

ANSWER : BC, BD, BCD\\