AIIMS 2018 Physics Magnetic Force on Moving Charges MCQ Question
Assertion: Magnetic field can not change K.E. moving charge.
Reason: Magnetic field can not change velocity vector.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
Correct Answer
Detailed Explanation
A magnetic field exerts a force on a moving charge that is perpendicular to both the velocity vector and the magnetic field direction, resulting in a change in the direction of the velocity vector without altering its magnitude. This means that while the kinetic energy (KE = ½mv²) remains constant for a charge moving at a constant speed, the velocity vector can change due to the magnetic force. Therefore, option C is correct because the effect of the magnetic field on the charge's velocity depends on the charge's initial conditions, such as its velocity and the orientation of the magnetic field. Options A and B are incorrect as they misinterpret the relationship between magnetic fields and kinetic energy, while options C and D do not fully capture the dependency on the charge's characteristics and the magnetic field's orientation.
Found an issue with this question?