Question

A circular coil having N turns and radius r carries a current I. It is held in the XZ plane in a magnetic field B `hat"i".` The torque on the coil due to the magnetic field is: ____________.

विकल्प

• `("Br"^2"I")/(pi"N")`

• `"B"pi"r"^2"IN"`

• `("B"pi"r"^2"I")/"N"`

• Zero

Answer 1

A circular coil having N turns and radius r carries a current I. It is held in the XZ plane in a magnetic field B `hat"i".` The torque on the coil due to the magnetic field is: `"B"pi"r"^2"IN"`.

Explanation:

`absvectau = abs(vec"m" xx vec"B") = "mB"  "sin"  theta`

`therefore absvectau = "NIA" xx "B"  "sin"  90°`

`therefore tau = "NI" (pi"r"^2) "B" xx 1`

`= "B" pi"r"^2 "IN"`