A uniform magnetic field $\vec{B}$ is established along the positive z-direction. A rectangular loop of sides 'a' and 'b' carries a current of I as shown in figure. The torque in the loop is:

IabB \((\hat{i})\)

The correct answer is Option (3) → $IabB(\hat{i})$

Given,

I = Current

a, b = side of rectangle ($l$)

⇒ Area = a × b = ab

B = Magnetic field

θ = Angle between $\vec B$ and $\vec I$

$τ=NIAB\sin θ$

$=IabB(\hat i)$