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Q.
A charged particle would continue to move with a constant velocity in a region wherein, which of the following conditions is not correct?
Moving Charges and Magnetism
Solution:
We know,
A body moves with a constant velocity only of there is no net external torque or force.
Case A
$E =0$ no net Electric force
$B \neq 0$ no net magnetic force when $v$ is perpendicular to $B$
Case B
$E \neq 0, B \neq 0$
There is net Electric as well as magnetic Force, but there is case when both get balanced.
Case C
$E \neq 0$, Electric force not exists,
$B \neq 0$ magnetic force exist.
Here, one of them os non zero and imbalanced.
Hence it is case when the condition fails.
Case D
$E =0, B =0$
Here neither magnetic force exist nor the Electric force.