A circular wheel with 10 spokes with its plane vertical along East-West is rotating about its natural axis with a uniform speed 100 revolutions per minute in the earth's magnetic field. Radius of the wheel is $0.3 \mathrm{~m}$. If the emf induced between the centre of the wheel and the rim is $3 \pi \mu \mathrm{V}$, angle of dip at the place is (Vertical component of the earth's magnetic field $\mathrm{B}_{\mathrm{V}}=15 \mu \mathrm{T}$ )

• A

  1. $\tan ^{-1}\left(\frac{1}{2}\right)$
• B

  $\tan ^{-1}\left(\frac{4}{5}\right)$
• C

  $\tan ^{-1}\left(\frac{3}{5}\right)$
• Correct answer
  D

  $\tan ^{-1}\left(\frac{3}{4}\right)$

Hence, the correct answer is option: 'D'.