Magnetics 6 Question 25
28. A metallic block carrying current $I$ is subjected to a uniform magnetic induction $\mathbf{B}$ as shown in figure. The moving charges experience a force $\mathbf{F}$ given by …… which results in the lowering of the potential of the face.
Assume the speed of the charges to be $v$.
$(1996,2 M)$
Analytical & Descriptive Questions
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Answer:
Correct Answer: 28. $e v B \hat{\mathbf{k}}, ABCD$ 29. $\omega _{\max }=\frac{D T _0}{B Q R^{2}}$
Solution:
In metals, charge carries are free electrons. Current is in positive direction of $x$-axis. Therefore, charge carries will be moving in negative direction of $x$-axis.
$$ \begin{aligned} \mathbf{F} _m=q(\mathbf{v} \times \mathbf{B}) & =(-e)(-v \hat{\mathbf{i}}) \times(B \hat{\mathbf{j}}) \\ \mathbf{F} _m & =e v B \hat{\mathbf{k}} \end{aligned} $$
Due to this magnetic force, electrons will be collecting at face $A B C D$, therefore lowering its potential.
