Question 175: Magnetism and Matter

Question

A square loop of side 2$$a$$, and carrying current
I, is kept in XZ plane with its centre at origin.
A long wire carrying the same current I is
placed parallel to the z-axis and passing
through the point (0, b, 0), (b >> a). The
magnitude of the torque on the loop about zaxis is given by :

Accepted Answer

We know, $$	au  = MB\sin 	heta $$
Here M = IA = I(2a)
2
= 4a
2
I
B = $${{{\mu _0}I} \over {2\pi b}}$$
Angle between B and M = 90
o
$$ 	herefore $$ $$	au  = \left( {4{a^2}I} ight)\left( {{{{\mu _0}I} \over {2\pi b}}} ight)\sin 90^\circ $$
= $${{2{\mu _0}{I^2}{a^2}} \over {\pi b}}$$

Answer

$${{2{\mu _0}{I^2}{a^2}} \over {\pi b}}$$

Answer

$${{{\mu _0}{I^2}{a^2}} \over {2\pi b}}$$

Answer

$${{{\mu _0}{I^2}{a^3}} \over {2\pi {b^2}}}$$

Answer

$${{2{\mu _0}{I^2}{a^3}} \over {\pi {b^2}}}$$

Magnetism and Matter

A square loop of side 2$a$, and carrying current I, is kept in XZ plane with its centre at origin. A long wire carrying the same current I is placed parallel to the z-axis and passing through the point (0, b, 0), (b >> a). The magnitude of the torque on the loop about zaxis is given by :

Choose the correct answer: