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CUET · PHYSICS · PYQ PAPER 2023

A magnetic needle free to rotate in a vertical plane parallel to the magnetic meridian has its north tip pointing down at \(30^{\circ}\) with the horizontal. The horizontal component of the earth's magnetic field at the place is B . The strength of the earth's magnetic field at the place is :

  1. A \(\frac{2 B}{\sqrt{3}}\)
  2. B \(\frac{ B }{\sqrt{3}}\)
  3. C \(B \sqrt{2}\)
  4. D 2 B
Verified Solution

Answer & Solution

Correct Answer

(A) \(\frac{2 B}{\sqrt{3}}\)

Step-by-step Solution

Detailed explanation

\(B_H = B_E \cos \delta\) \(B_E = \frac{B_H}{\cos \delta}\) \(B_E = \frac{B}{\cos 30^{\circ}}\) \(B_E = \frac{B}{\frac{\sqrt{3}}{2}}\) \(B_E = \frac{2 B}{\sqrt{3}}\)