NEET 2023 Phase 2 · PhysicsLorentz forcePrevious Year Question
A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected in the region such that its velocity is pointed along the direction of fields, then the electron
Answer: (A) Speed will decrease. Answer: (A) Solution: Velocity v is parallel to B, so the magnetic force F = q(v × B) = 0 → no deflection.
- A.Speed will decrease✓
- B.Speed will increase
- C.Will turn towards right of direction of motion
- D.Will turn towards left of direction of motion
Correct Answer
(A) Speed will decrease
Solution & Explanation
Answer: (A) Solution: Velocity v is parallel to B, so the magnetic force F = q(v × B) = 0 → no deflection. Only the electric force acts. For an electron (charge −e), F = −eE, i.e. opposite to E. Since v points along E, the force is opposite to v → the electron decelerates. Therefore its speed will decrease.
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