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Question

Question: Two short magnets with their axes horizontal and perpendicular to the magnetic meridian are placed w...

Two short magnets with their axes horizontal and perpendicular to the magnetic meridian are placed with their centres 40 cm east and 50 cm west of magnetic needle. If the needle remains undeflected, the ratio of their magnetic moments M1:M2M _ { 1 } : M _ { 2 } is

A

4 : 5

B

16 : 25

C

64 : 125

D

2:52 : \sqrt { 5 }

Answer

64 : 125

Explanation

Solution

For null deflection

M1M2=(d1d2)3=(4050)3=64125\frac { M _ { 1 } } { M _ { 2 } } = \left( \frac { d _ { 1 } } { d _ { 2 } } \right) ^ { 3 } = \left( \frac { 40 } { 50 } \right) ^ { 3 } = \frac { 64 } { 125 }