A wire is bent in the form of an equilateral triangle PQR of side 10 cm and carrise a current of 5.0 A. It is placed in a magnetic field B of magnitude 2.0 T directd perpendicularly to the plane of the loop. Find the forces on the three sides of the triangle.

Explanation

Suppose the field and the current have directions as shown in figure. The force on PQ is
`vecF_(1)=iveclxxvecB`
or, `F_(1)=5.0Axx10cmxx2.0T=1.0N`
The rule of vector product shows that the force `F_(1)` is perpendicular to PQ and is directed towards the inside of the triangle.
The forces `vecF_(2)` and `vecF_(3)` on QR and RP can also be obtained similarly. Both the forces are 1.0 N directed perpendicularly to the respective sides and towards the inside of the triangle.
The three forces `vecF_(1),vecF_(2)andvecF_(3)` will have zero resultant, so that there is no net magnetic force on the triangle. This result can be generalised. Any closed current loop, placed in a homogeneous magnetic field, does not experience a net magnetic force.