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NEET 2015
Exam
NEET
Year
2015
Subject
Physics
Chapter
Magnetic Effects of Current

NEET 2015 · Physics · Magnetic Effects of Current

An electron moving in a circular orbit of radius r makes n...

An electron moving in a circular orbit of radius rr makes nn rotations per second. The magnetic field produced at the center has magnitude:

Options

  1. Aμ0ne2\pir\dfrac{{\mu}_{0}ne}{2\pir}
  2. BZero
  3. Cμ0n2er\dfrac{{\mu}_{0}{n}^{2}e}{r}
  4. Dμ0ne2r\dfrac{{\mu}_{0}ne}{2r}

Correct answer

D. μ0ne2r\dfrac{{\mu}_{0}ne}{2r}

Step-by-step solution

If an electron is doing nn revolutions per second then we can say the current is,
i=qT=eTwe know thatT=1n.i = \dfrac{q}{T} = \dfrac{e}{T}\text{we know that}T = \dfrac{1}{n} .
⇒i=eT=ne⇒ i = \dfrac{e}{T} = ne

Now, magnetic field at the center of a circular loop is
B=μ0i2r=μ0ne2rB = \dfrac{{\mu}_{0}i}{2r} = \dfrac{{\mu}_{0}ne}{2r}

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