Torques `tau_(1)` and `tau_(2)` are required for a magnetic needle to remain perpendicular to the magnetic fields at two different places. The magnetic field at those places are B1 and B2 respectively, then `(B_(1))/(B_(2))` is

Options

A. `(tau_(2))/(tau_(1))`
B. `(tau_(1))/(tau_(2))`
C. `(tau_1+ tau_2)/(tau_1 - tau_2)`
D. `(tau_1- tau_2)/(tau_1 + tau_2)`

Answer

B

Explanation

Torque , ` tau=MB sin theta `
`tau_(1)=MB_(1) sin 90^(@)=MB_(1)`
` tau=(2)=MB_(2) sin 90^(@)=MB_(2)`
` or (MB_(1))/(MB_(2))=(tau_(1))/(tau_(2))`
`:. (B_(1))/(B_(2))=(tau_1)/(tau_2)`