Q3.
A
A wire of radius 0.5cm carries a current of 100A
which is informly distributed over its cross-
section find the magretic field
at 0.1cm from the axis of the wire.
Answers
Answered by
2
Explanation:
Ampere circuit law
B×2πr=λ
w
I
a=3.0mm=3×10
−3
I= total current enclosed
in the area of circle of radius r
I=
m
2
100mp
(a) area circule of radius r=2.0mm=2×10
−3
m will be A=AR
2
=4π×10
−6
m
2
⇒ current I=IA=100×4π×10
−6
amp
so field wire will be given by
B×2πr=λ
w
I=λ
0
×4π×10
−6
×100
⇒B=
r
2λ
w
×10
−4
=
2×10
−3
2×4π×10
−11
Tesla
putting (λ
w
=4π×10
−7
) m.k.s unit
or
B=4π×10
−8
Tesla
(b) area circle of radiusr=4.0mm
which is more than radius of wire (a=3mm)
so current =total current
=3×π(3×10
−3
)
2
=9π×10
−4
field
B=
2πr
λ
0
I
=
2π× 4×10
−3
4π×10
−7
×9π×10
−4
2
9π
×10
−8
Tesla
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