TBR cbt 5 - PS#20

[attixx]

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I'm a little confused about this one.

Which of the following accurately describes the torque on a loop in a generator (essentially a solenoid creating a magnetic force to turn a magnet in the center) . N is the number of turns in the wire coil, I is the current, A is the area of the loop.

The answer is torque = (N*I*A)*B*sin(angle)

I understand everything but the area part, which TBR fails to elaborate on. Why would increasing the area of a solenoid increase the magnetic force/torque?

Is it just because there is more wire for current to create a magnetic force in a bigger loop?

Here's a picture if needed:

 

[Bayonetwork]

Are you sure A is not referring to the cross sectional area of the current carrying wire of the solenoid. If it is then all thats happening is an increased current.

If for some reason A is referring to the total area of the coil and not cross sectional area or length/turns then I would guess a greater total area of coil exerts a greater magnetic moment (dipole) on the magnet. In other words it increases the magnetic flux applied to the magnet.

 

[ridethecliche]

You increase the strength of a magnet by increasing the coils. More coils-->more current-->More force due to stronger mag field.

Number of turns times area of each turn leads to the calculation for the mag field.


http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/solenoid.html