A long straight wire carries a certain current and produces a magnetic field 2 × 10^ -4 Weber m^2 at a perpendicular distance of 5 ~cm from the wire. An electron situated at 5 ~cm from the wire moves with a velocity

NEET 2013

NEET 2013 · Physics · Magnetic Effects of Current

A long straight wire carries a certain current and produces a...

A long straight wire carries a certain current and produces a magnetic field

2 \times 10^{-4} \frac{\text{ Weber }}{\mathrm{m}^2}

at a perpendicular distance of

5 \mathrm{~cm}

from the wire. An electron situated at

5 \mathrm{~cm}

from the wire moves with a velocity

10^7 \mathrm{~m} / \mathrm{s}

towards the wire along perpendicular to it. The force experienced by the electron will be (change on electron

1.6 \times 10^{-19} \mathrm{C}

)

B. $3.2 \times 10^{-16} \mathrm{~N}$

From the question Velocity of electron

=10^7 \mathrm{~m} / \mathrm{s}

Magnetic field

B=2 \times 10^{-4} \mathrm{~Wb} / \mathrm{m}^2

Then magnitude of force experienced by the electron i.e. F=e v

\mathrm{~B} \sin \theta\{\because V and B

are prependicular to each other

\begin{aligned}& =e v \mathrm{~B} \sin90^{{}^{\circ}} \\ & =1.6 \times10^{-19} \times10^7 \times2 \times10^{-4} \times1 \\ & =3.2 \times10^{-16} \mathrm{~N} \end{aligned}