Question

Consider the following statements.
A magnetic field:
$1$. never exerts a force on a charged particle.
$2$. always exerts a force on a charged particle.
$3$. exerts a force on a charged particle if it is moving across the magnetic lines of force.
$4$. exerts a force on a charged particle if it is moving along the magnetic lines of force.
Which of the statement(s) given is/are correct?

• A. Only $3$
• B. Only $4$
• C. $1$ and $2$
• D. $1,2,3$ and $4$

Answer 1

Answer: (A)

Only $3$

Magnetic force experienced by a charged particle $\overrightarrow{F}=q(\overrightarrow{v}\times \overrightarrow{B})$
If $\overrightarrow{v}\parallel \overrightarrow{B}$, then $\overrightarrow{F}=0$
So the magnitude of force is non zero only when a charged particle moves across the magnetic field lines of forces.