If the angles of dip at two places are \(30^{\circ}\) and \(45^{\circ}\) respectively, then the ratio of…

If the angles of dip at two places are \(30^{\circ}\) and \(45^{\circ}\) respectively, then the ratio of horizontal components of earth's magnetic field at the two places will be
  1. \(\sqrt{3}: \sqrt{2}\)
  2. \(1: \sqrt{2}\)
  3. \(1: \sqrt{3}\)
  4. \(1: 2\)

Solution

If \(B_e\) be the earth's net magnetic field, then the ratio of horizontal components of earth's magnetic field at the two places is given as \(\begin{aligned} \frac{H_1}{H_2} & =\frac{B_e \cos \delta_1}{B_e \cos \delta_2}=\frac{\cos \delta_1}{\cos \delta_2} \\ & =\frac{\cos 30^{\circ}}{\cos 45^{\circ}} \quad\left[\because \delta_1=30^{\circ}, \delta_2=45^{\circ}\right] \\ & =\frac{\sqrt{3} / 2}{1 / \sqrt{2}}=\frac{\sqrt{3}}{\sqrt{2}} \\ \therefore \quad H_1: H_2 & =\sqrt{3}: \sqrt{2} \end{aligned}\)

Asked in: AP EAMCET 2020 (17 Sep Shift 2)

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