A rod AB moves with a uniform velocity v in a uniform magnetic fi… - Vidyadip

MCQ

A rod $AB$ moves with a uniform velocity $v$ in a uniform magnetic field as shown in figure.

A
The rod becomes electrically charged.
✓
The end $A$ becomes positively charged.
C
The end $B$ becomes positively charged.
D
The rod becomes hot because of Joule heating.

✓

Answer

Correct option: B.

The end $A$ becomes positively charged.

The end $'A\ '$ becomes, positively charged. Because magnetic field exerts an average Force $\overrightarrow{\text{F}}_0=\text{q}\vec{\text{v}}\times\vec{\text{B} } n$ each free electron where $q = 1. 6 \times 10^{19}C$ is the charge on the electron. This Force is towards $AB$ and hence the free electrons will move towareds $B$. Negative charge is accumulated at $'B\ '$ and positive charge appears at $A.$

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