What is meant by uniform magnetic field?

In summary: It is often used in experiments and calculations as it simplifies the analysis of magnetic fields. Non-stick cookware is a substance commonly used as a coating to reduce friction, as it allows for smoother movement and less resistance between surfaces. In summary, the force of friction is independent of the area of the two surfaces in contact because it is strictly proportional to the applied normal force, which is equal to the normal force from the surface. A substance commonly used for coating to reduce friction is non-stick cookware. A uniform magnetic field is one in which the magnetic flux density is constant and is often used in experiments and calculations.
  • #1
ritwik06
580
0
Why is the force of friction independent of the area of the 2 surfaces in contact? Name a subtance used for coating to reduce friction. Is it paint?

What is meant by uniform magnetic field?
 
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  • #2
Please show some work, as we cannot help you until you do so. Do you have any thoughts about the questions?
 
  • #3
cristo said:
Please show some work, as we cannot help you until you do so. Do you have any thoughts about the questions?

i think that surface area in contact should affect friction. As in the case of ball bearings, the surface in contact is quite less.

I don't know about uniform magnetic field!
 
  • #4
The force of friction at any point is proportional to the local pressure at that point*, i.e, doubling the pressure there doubles the friction.

The net "pressure force" F (or applied normal force) is gained by summing up the pressures at all points:
[tex]F=\int_{S}pdA[/tex]
where S is the surface we sum over, p is the local pressure, and dA the differential area element.

Now, the proportionality factor between the force of friction and the local pressure will most likely only vary significantly if the contact surface properties themselves vary significantly**.
So, if the contact surface can be regarded as relatively homogenous in material properties, the local force of friction can be written as:
[tex]dF_{fric}=\mu{p}dA[/tex]
where [itex]dF_{fric}[/itex] is the local friction force
and [itex]\mu[/itex] the constant proportionality factor.

Thus, the net friction force is given by:
[tex]F_{fric}=\int_{S}dF_{fric}=\int_{S}\mu{p}dA=\mu\int_{S}pdA=\mu{F}[/tex]

Thus, the force of friction is strictly proportional to the applied normal force, which again equals the normal force N from the surface, since the objects don't slide into each other.
Thus, the friction force is proportional to N.

In particular, in so far as the applied force remains the same, whereas the contact surface is changed, no change will be seen in the net friction force.

It is LOCALLY stronger, just as the local pressure is stronger, but the total surface is less, so the whole balances neatly.


*This is our starting HYPOTHESIS, that has ample empirical verification.

** The friction coefficient happens to be EXTREMELY sensitive to a lot of factors: temperature, presence of material impurities and so on.
This by no means reduce the validity of the argument below, but does, indeed, limit the usefulness of the model.
 
Last edited:
  • #5
Hint to one of the questions: Think about non-stick cookware
 
  • #6
A uniform magnetic field is one in which the magnetic flux density is constant throughout any area taken perpendicular to its direction.
 

1. What is a uniform magnetic field?

A uniform magnetic field is a region in space where the strength and direction of the magnetic field are constant. This means that the magnetic field lines are equally spaced and parallel to each other.

2. How is a uniform magnetic field created?

A uniform magnetic field can be created by passing an electric current through a straight wire or by using a magnet with a uniform shape, such as a bar magnet or a solenoid.

3. What are the properties of a uniform magnetic field?

A uniform magnetic field has a constant strength and direction throughout the region. It also exerts a force on moving charged particles, causing them to follow a curved path known as a Lorentz force.

4. What are the practical applications of a uniform magnetic field?

A uniform magnetic field has various practical applications, including in particle accelerators, mass spectrometers, and magnetic resonance imaging (MRI) machines. It is also used in compasses, motors, and generators.

5. How does a uniform magnetic field differ from a non-uniform magnetic field?

In a non-uniform magnetic field, the strength and direction of the magnetic field vary throughout the region. This can be seen in the non-uniform spacing and direction of the magnetic field lines. Non-uniform magnetic fields can be created by using multiple magnets or shaping a magnet in a certain way.

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