Question

When two magnetic moments are compared using equal distance method the deflections produced are 45^o and 30^o. If the length of magnets are in the ratio 1 : 2, the ratio of their pole strengths is

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

Answer 1

Answer: (D)

$2 \sqrt { 3 } : 1$

Answer 2

$\frac { M _ { 1 } } { M _ { 2 } } = \frac { \tan \theta _ { 1 } } { \tan \theta _ { 2 } } \Rightarrow \frac { m _ { 1 } L _ { 1 } } { m _ { 2 } L _ { 2 } } = \frac { \tan \theta _ { 1 } } { \tan \theta _ { 2 } }$

$\Rightarrow \frac { m _ { 1 } } { m _ { 2 } } = \frac { 2 } { 1 } \times \frac { \tan 45 ^ { \circ } } { \tan 30 ^ { \circ } } = \frac { 2 \sqrt { 3 } } { 1 }$