Question

Magnetic field due to a bar magnet 2cm long having a pole strength of 100 Am at a point 10 cm

from each pole is

a) 2  10-4 T b) 8  10-4T c) 2  10-5 T d) 4  10-4 T​

Answer 1

Answer:

Magnetic induction on axial line,B=

4π

μ

0

.

(d

2

−l

2

)

2

2Md

length of magnet=2l=0.01m=10cm

or,l=5cm

M=2ml=2×120×0.05

d=20cm

∴B=

4π

μ

∘

×

(0.2

2

−0.05

2

)

2

2×2×120×0.05×0.2

=341.33×1o

−6

T

=3.4×10

−4

T