13 - Moving charge magnetism and force in magnetic field Questions Answers

$$\begin{gathered} Magnetic torque = \overrightarrow{M}\times \overrightarrow{B}=i\overrightarrow{A}\times \overrightarrow{B} \\ Torque due to gravity about the point of \\ circumference = \overrightarrow{R}\times m\overrightarrow{g} \\ Now compare the two \end{gathered}$$Inform for any issue

method given by BONEY is correct but formula is not correct

it should be B = 4×{ (μ₀I) / 4πR } × [sinθ₁+ Sinθ₂]

the resultant dipole moment is √2M  thus  the resultant magnetic  field is  μ2√2M/4πd³   (ans)

this answer is given by sarika and is correct answer

B = μ₀/2 * i/r

and i = e/T

and T = 2πr/v

solve

when charge will move from first dee to second dee it will gain qV and on returning to first dee it will gain qV again so in one revolution it will gain 2qV so in n revolutions it will gain 2qVn