Determining the Magnetic Force on a Moving Charged Particle

In summary, to find the magnitude of the force exerted on an electron moving in a magnetic field, use the equation F=qvBsin(theta), where q is the charge of the electron, v is its velocity, B is the strength of the magnetic field, and theta is the angle between the velocity and the field. Units must be carefully considered in calculations, as the charge of an electron is given in Coulombs, not fundamental charge.
  • #1
robera1
22
0

Homework Statement


If the magnetic field of the wire is 2.5×10^−4 and the electron moves at 1.0×10^7 , what is the magnitude of the force exerted on the electron?

Homework Equations


F=qvBsin(theta)

The Attempt at a Solution


Sin(theta) = sin90 = 1
q = -1
v = 1e7
B = 2.5e-4
So, (-1)x(1e7)x(2.5e-4) = -2500, but that is not the right answer. What am I doing wrong?
 
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  • #2
2.5×10^−4 what? Tesla? Gauss? What about 1.0×10^7? Where are the electron and wire in space? How are they moving? It's impossible to figure out what you might have been doing wrong without knowing the full problem.
 
  • #3
Oh, okay. This is all of the information they give...

Learning Goal: To practice Tactics Box 24.2 Determining the magnetic force on a moving charged particle.

When a particle of charge moves with a velocity in a magnetic field , the particle is acted upon by a force exerted by the magnetic field. To find the direction and magnitude of this force, follow the steps in the following Tactics Box. Keep in mind that the right-hand rule for forces shown in step 2 gives the direction of the force on a positive charge. For a negative charge, the force will be in the opposite direction.

TACTICS BOX 24.2 Determining the magnetic force on a moving charged particle
Note the direction of v and B, and find the angle [alpha] between them.
The force is perpendicular to the plane containing v and B. The direction of F is given by the right-hand rule.
The magnitude of the force is given by F = qvBsin[alpha]

Part C
If the magnetic field of the wire is 2.5×10^−4 T and the electron moves at 1.0×10^7 m/s, what is the magnitude F of the force exerted on the electron?
 
  • #4
Okay... well, I'm guessing there's a diagram or something that goes along with that, that shows the wire, the electron, and the angle between the electron's velocity and the magnetic field? Not that it matters, as long as you've got the right angle (90 degrees).

Anyway, to continue one point from the previous post: you must keep track of units in your calculations. Think about this: what are the units for q, v, B? what unit is your previous answer (-2500) in?
 
  • #5
Well, the answer is supposed to be in N.
And, since I am multiplying C, T, and m/s, then the -2500 should be in N also
 
  • #6
robera1 said:

Homework Statement


If the magnetic field of the wire is 2.5×10^−4 and the electron moves at 1.0×10^7 , what is the magnitude of the force exerted on the electron?

Homework Equations


F=qvBsin(theta)

The Attempt at a Solution


Sin(theta) = sin90 = 1
q = -1
v = 1e7
B = 2.5e-4
So, (-1)x(1e7)x(2.5e-4) = -2500, but that is not the right answer. What am I doing wrong?

The charge on an electron is [itex]-1.60\times 10^{-19}C[/itex]
 
  • #7
Consider your charge. You multiplied by (-1), but what are the units of that? Units of fundamental charge, which is NOT 1 C.

EDIT: Lol, What he said ^
 
  • #8
Fantastic! I got the answer... thanks!
 

1. What is the equation for determining the magnetic force on a moving charged particle?

The equation for determining the magnetic force on a moving charged particle is F = qvBsinθ, where F is the magnetic force, q is the charge of the particle, v is the velocity of the particle, B is the magnetic field, and θ is the angle between the velocity and magnetic field.

2. How does the velocity of the charged particle affect the magnetic force?

The velocity of the charged particle is directly proportional to the magnetic force. This means that as the velocity increases, so does the magnetic force, and vice versa.

3. What is the direction of the magnetic force on a moving charged particle?

The direction of the magnetic force is perpendicular to both the velocity of the particle and the magnetic field. This is known as the right-hand rule: if you point your thumb in the direction of the velocity and your fingers in the direction of the magnetic field, the direction your palm is facing represents the direction of the magnetic force.

4. How does the charge of the particle affect the magnetic force?

The charge of the particle is also directly proportional to the magnetic force. This means that a particle with a higher charge will experience a stronger magnetic force than a particle with a lower charge, given the same velocity and magnetic field.

5. What factors can affect the magnetic force on a moving charged particle?

The magnetic force on a moving charged particle can be affected by the velocity of the particle, the charge of the particle, and the strength and direction of the magnetic field. Additionally, the angle between the velocity and magnetic field can also impact the magnitude of the magnetic force.

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