Chapter 22, Problem 1OQ

To determine

The situation in which a spatially uniform magnetic field cannot exert a magnetic force on a particle.

Answer to Problem 1OQ

Option (c) and (e).

Explanation of Solution

Write the formula for magnetic force (Lorentz force)

  $\begin{array}{c}F=qv\times B\\ =qvB\sin \theta \end{array}$        (I)

Here, $F$ is the magnetic force, $q$ is charge of the particle, $\theta$ is the angle between $v$ and $B$ ,

and $B$ is the magnitude of magnetic field.

If the particle is not charged or moves at an angle $\theta =0°$, a uniform magnetic field cannot exert a magnetic force on a particle. As the magnetic field is depended upon the $q$ and the $\overrightarrow{B}$.

Conclusion

A spatially uniform magnetic field can exert a magnetic force on the particle which is charged. Thus, option (a) is incorrect.

A spatially uniform magnetic field that moves perpendicular to the magnetic field can exert magnetic force on the particle. Therefore, option (b) is incorrect.

A spatially uniform magnetic field cannot exert a magnetic force on the particle moving parallel to the magnetic field. Thus, option (c) is correct.

When the magnitude of the magnetic field changes, a spatially uniform magnetic field can exert a magnetic force on the particle. Thus, option (d) is incorrect.

A magnetic field that is spatially uniform cannot exert a magnetic force on the resting partcle Thus, option (e) is correct.