Question

At 15cm, you measure a magnetic field of about 1.5 mT. If the magnetic field of a permanent magnet is dipole-like in this region, what is the closest magnetic field you would expect to measure at 30cm from the magnet?

Answer 1

Answer:

closest magnetic field is  0.2 MT

Explanation:

given data

B = 1.5 mt

r = 30 cm

solution

as here magnetic filed due to magnetic dipole is inversely is inversely proportion to distance cube  that is

B ∝ $\frac{1}{r^3}$    ................1  

heer r1 is 15 cm and r2 is 30 cm

so magnetic field is

$\frac{B2}{1.5} = (\frac{15}{30} )^3$  

solve we get

B2 = 0.2 MT