(c) $B^{2} = B_{V}^{2} + B_{H}^{2} \Rightarrow B_{V} = \sqrt{B^{2} - B_{H}^{2}} = \sqrt{(0.5)^{2} - (0.3)^{2}} = 0.4$ Now $\tan\phi = \frac{B_{V}}{B_{H}} = \frac{0.4}{0.3} = \frac{4}{3} \Rightarrow \phi = \tan^{- 1}\left( \frac{4}{3} \right)$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.