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Dipole in an external electric field

  • Thread starter Prashasti
  • Start date
  • #1
63
2

Homework Statement


Why isn't the expression for torque on a dipole kept in an external electric field ExP? Why is it PxE?
No such indication has been given in any of the derivations, that it is mandatory for it to be PxE, so why can't it be ExP?

2. The attempt at a solution
Is it all about experiments?
 

Answers and Replies

  • #2
gneill
Mentor
20,792
2,770

Homework Statement


Why isn't the expression for torque on a dipole kept in an external electric field ExP? Why is it PxE?
No such indication has been given in any of the derivations, that it is mandatory for it to be PxE, so why can't it be ExP?

2. The attempt at a solution
Is it all about experiments?
What's the essential difference in the cross products A x B versus B x A?
 
  • #3
63
2
The direction of the resultant of A x B is just opposite to that of B x A...
 
  • #4
gneill
Mentor
20,792
2,770
The direction of the resultant of A x B is just opposite to that of B x A...
Right. So it comes down to the definitions of positive or negative directions for quantities in the chosen coordinate system. This includes assumed directions for positive or negative torques, angular velocities, etc., which are vector quantities (or pseudo vector quantities in some cases, but that's another topic).
 

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