In Fig., find the resultant magnetic force and torque about C.

Explanation

`vecF_("nett")=I.2R.B`
`because` wire is equivalent to
Point on each element is radially outward :`t_(c)=0` point about
`P=underset(0)overset(pi)int[i(Rd theta)B sin 90^(@)]R sin theta`
`=2IBR^(2)`