Easy MCQ +4 / -1 PYQ · JEE Mains 2020

A charged particle carrying charge 1 $\mu$C is moving
with velocity $\left( {2\widehat i + 3\widehat j + 4\widehat k} \right)$ ms–1. If an external
magnetic field of $\left( {5\widehat i + 3\widehat j - 6\widehat k} \right)$× 10–3 T exists in the region where the particle is moving then the
force on the particle is $\overrightarrow F$ × 10–9 N. The vector $\overrightarrow F$ is :

  1. A ${ - 0.30\widehat i + 0.32\widehat j - 0.09\widehat k}$
  2. B ${ - 300\widehat i + 320\widehat j - 90\widehat k}$
  3. C ${ - 30\widehat i + 32\widehat j - 9\widehat k}$ Correct answer
  4. D ${ - 3.0\widehat i + 3.2\widehat j - 0.9\widehat k}$

Solution

Given, <br><br>${\overrightarrow V }$ = $\left( {2\widehat i + 3\widehat j + 4\widehat k} \right)$ ms<sup>–1</sup> <br><br>${\overrightarrow B }$ = $\left( {5\widehat i + 3\widehat j - 6\widehat k} \right)$× 10<sup>–3</sup> T <br><br>q = 1 $\mu$C <br><br>$$\overrightarrow F = q\left( {\overrightarrow V \times \overrightarrow B } \right)$$ <br><br>= $${10^{ - 6}} \times {10^{ - 3}} \times \left| {\matrix{ {\widehat i} &amp; {\widehat j} &amp; {\widehat k} \cr 2 &amp; 3 &amp; 4 \cr 5 &amp; 3 &amp; { - 6} \cr } } \right|$$ <br><br>= (${ - 30\widehat i + 32\widehat j - 9\widehat k}$) $\times$ 10<sup>-9</sup>

About this question

Subject: Physics · Chapter: Magnetic Effects of Current · Topic: Biot-Savart Law

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