Q 11 :

As shown in the figure, a current of 2 A flowing in an equilateral triangle of side 43cm. The magnetic field at the centroid O of the triangle is                 [2023]

[IMAGE 226]

(Neglect the effect of earth's magnetic field.)

  • 43×10-4 T

     

  • 43×10-5 T

     

  • 3×10-4 T

     

  • 33×10-5 T

     

(4)

d tan 60°=23

d=2 cm

B=3×μ0i2πdsin60°

=3×2×10-7×22×10-2×32

=33×10-5



Q 12 :

Two long parallel wires carrying currents 8 A and 15 A in opposite directions are placed at a distance of 7 cm from each other. A point P is at equidistant from both the wires such that the lines joining the point P to the wires are perpendicular to each other. The magnitude of magnetic field at P is ________ ×10-6 T. (Given: 2=1.4)     [2023]



(68)

Magnetic fields due to both wires will be perpendicular to each other.

[IMAGE 227]

B1=μ0i12πd,  B2=μ0i22πd

Bnet=B12+B22=μ02πdi12+i22

4π×10-72π×(72)×10-2×82+152 (d=72 cm)

=68×10-6 T



Q 13 :

An electron in a hydrogen atom revolves around its nucleus with a speed of 6.76×106 ms-1 in an orbit of radius 0.52Å. The magnetic field produced at the nucleus of the hydrogen atom is _________ T.                       [2023]



(40)

Magnetic field due to moving charge

B=μ04πqvsinθr2

B=μ04πevsin(π/2)r2

B=10-7×1.6×10-19×6.76×1060.52×0.52×10-20

  B=40 T