14. Consider the motion of a positive point charge in a region where there are simultaneous uniform electric and magnetic fields $\vec { E } = E _ { 0 } \hat { j }$ and $\vec { B } = B _ { 0 } \hat { j }$. At time $t = 0$, this charge has velocity $\vec { v }$ in the $x - y$ plane, making an angle $\theta$ with the $x$-axis. Which of the following option(s) is(are) correct for time $t > 0$ ?\\
(A) If $\theta = 0 ^ { \circ }$, the charge moves in a circular path in the $x - z$ plane.\\
(B) If $\theta = 0 ^ { \circ }$, the charge undergoes helical motion with constant pitch along the $y$-axis.\\
(C) If $\theta = 10 ^ { \circ }$, the charge undergoes helical motion with its pitch increasing with time, along the $y$-axis.\\
(D) If $\theta = 90 ^ { \circ }$, the charge undergoes linear but accelerated motion along the $y$-axis.

\section*{ANSWER : CD}
\begin{enumerate}
  \setcounter{enumi}{14}
  \item A person blows into open-end of a long pipe. As a result, a high-pressure pulse of air travels down the pipe. When this pulse reaches the other end of the pipe,\\
(A) a high-pressure pulse starts traveling up the pipe, if the other end of the pipe is open.\\
(B) a low-pressure pulse starts traveling up the pipe, if the other end of the pipe is open.\\
(C) a low-pressure pulse starts traveling up the pipe, if the other end of the pipe is closed.\\
(D) a high-pressure pulse starts traveling up the pipe, if the other end of the pipe is closed.
\end{enumerate}

\section*{ANSWER : BD}
\section*{SECTION III: Integer Answer Type}
This section contains $\mathbf { 5 }$ questions. The answer to each question is a single digit integer, ranging from 0 to 9 (both inclusive).\\