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NEET 2023 · Moving Charge in a Magnetic Field

Moving Charge in a Magnetic Field question from NEET 2023

Q45NEET 2023Easy

Moving Charge in a Magnetic Field

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:

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Answer: (c)

  1. v⃗∥B⃗⇒\vec v \parallel \vec B \Rightarrow magnetic force −e(v⃗×B⃗)=0-e(\vec v\times\vec B) = 0, so no turning.
  2. Electric force on electron =−eE⃗= -e\vec E, opposite to E⃗\vec E, i.e. opposite to v⃗\vec v.
  3. The electron is decelerated along its line of motion.
  4. So the answer is (c) speed will decrease.
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