Question

At a certain place the angle of dip is 30° and the horizontal component of earth's magnetic field is 0.50 Oersted. The earth's total magnetic field is

• A. $\sqrt { 3 }$
• B. $1$
• C. $\frac { 1 } { \sqrt { 3 } }$
• D. $\frac { 1 } { 2 }$

Answer 1

Answer: (C)

$\frac { 1 } { \sqrt { 3 } }$

Answer 2

$B _ { H } = B \cos \phi ; \therefore B = \frac { B _ { H } } { \cos \phi } = \frac { 0.5 } { \cos 30 ^ { \circ } } = \frac { 0.5 } { \sqrt { 3 } / 2 } = \frac { 1 } { \sqrt { 3 } }$