question_answer

When a charged particle moving with velocity \[\vec{v}\] is subjected to a magnetic field of induction \[\vec{B},\] the force on it is non-zero. This implies that:                                                                             [AIPMT (S) 2006]

A)  angle between \[\vec{v}\] and \[\vec{B}\] is necessarily \[{{90}^{o}}\]

B)  angle between \[\vec{v}\] and \[\vec{B}\] can have any value other than \[{{90}^{o}}\]

C)       angle between \[\vec{v}\] and \[\vec{B}\] can have any value other than zero and \[{{180}^{o}}\]

D)       angle between \[\vec{v}\] and \[\vec{B}\] is either zero or \[{{180}^{o}}\] Correct Answer: C Solution : [c] When a charged particle q is moving in a uniform magnetic field \[\vec{B}\] with velocity \[\vec{v}\] such that angle between \[\vec{v}\] and \[\vec{B}\] be \[\theta ,\] then due to interaction between the magnetic field produced due to moving charge and magnetic field applied, the charge q experiences a force which is given by

\[F=qvB\sin \theta \]

If                      \[\theta ={{0}^{o}}\] or \[{{180}^{o}},\] then sin \[\theta =0\]

\[\therefore \]      \[F=qvB\sin \theta \]

Since, force on charged particle is non-zero, so angle between \[\vec{v}\] and \[\vec{B}\] can have any value other than zero and \[{{180}^{o}}\].