HSC Physics - Torque
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Transcript of HSC Physics - Torque
![Page 1: HSC Physics - Torque](https://reader036.fdocuments.in/reader036/viewer/2022062302/5877da391a28abaa6c8b6043/html5/thumbnails/1.jpg)
HSC Physics9.3 Motors and Generators
TORQUE
![Page 2: HSC Physics - Torque](https://reader036.fdocuments.in/reader036/viewer/2022062302/5877da391a28abaa6c8b6043/html5/thumbnails/2.jpg)
Torque is the tendency of a force to rotate an object about an axis, fulcrum or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist.
Torque is a force that produces rotation.
Torque has the symbol, , 𝞃and units of newton metres (Nm).
If the force is not perpendicular to the distance d it must be resolved into a perpendicular force using trigonometry as shown.
![Page 3: HSC Physics - Torque](https://reader036.fdocuments.in/reader036/viewer/2022062302/5877da391a28abaa6c8b6043/html5/thumbnails/3.jpg)
In electric motors, it is a conductor wound into a coil or loop that turns when torque is applied.
The force in the equation for torque comes from the motor effect:
F = BILsinθ
![Page 4: HSC Physics - Torque](https://reader036.fdocuments.in/reader036/viewer/2022062302/5877da391a28abaa6c8b6043/html5/thumbnails/4.jpg)
To see how the torque changes as the coil turns, it is best visualise the coil in only two dimensions.
![Page 5: HSC Physics - Torque](https://reader036.fdocuments.in/reader036/viewer/2022062302/5877da391a28abaa6c8b6043/html5/thumbnails/5.jpg)
As the coil turns the torque changes because the angle between the magnetic field lines and the plane of the coil (θ) is also changing.
The torque is maximum when the θ = 0 and zero when θ = 90°.
The force stays constant during rotation but the torque changes following a cos graph.
![Page 6: HSC Physics - Torque](https://reader036.fdocuments.in/reader036/viewer/2022062302/5877da391a28abaa6c8b6043/html5/thumbnails/6.jpg)
If a radial magnetic field is used instead, the field lines are curved between the north and south poles of the magnet.
The angle θ between the plane of the coil and the field lines is kept closer to zero as the coil rotates.
If θ is small the torque will be kept larger for longer during a rotation.