Direction of electron in magnetic field?

In summary, when an electron moves with a speed of 4.00x10^5 m/s in a uniform magnetic field of 3.2 T pointing south, and experiences an upward magnetic force of 1.00x10^-14 N, the possible directions it could be moving at that instant are approximately 182.8 and 357.2 degrees clockwise from south. This is calculated using the equation F=qvBsin(theta) and the left hand rule.
  • #1
vrobins1
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Homework Statement



An electron moves with speed 4.00 105 m/s in a uniform magnetic field of 3.2 T, pointing south. At one instant, the electron experiences an upward magnetic force of 1.00 10-14 N. In what possible directions might the electron be moving at that instant? Give your answers as angles clockwise from south (from 0° to 360°), in increasing degrees.

(I have to find two answers in degrees, both clockwise from south).

Homework Equations



F = qvBsin(theta)

The Attempt at a Solution



F = qvBsin(theta)

sin(theta) = F / qvB

= (1x10-14) / [(1.6x10-19)(4x105)(3.2)]

= .0488

theta = sin-1(.0488)

theta = 2.8

So my first angle was approximately 2.8. I subtracted that from 270 degrees ("south") to get my final angle of 267.2 degrees. Then I subtracted 2.8 from 180 to get my second angle, which was approximately 177.2. I subtracted THAT number from 270 degrees to get my final second angle of approximately 92.8 degrees. I thought that 267.2 and 92.8 were my answers, but they are coming up as incorrect. I also tried rounding to a whole number, which didn't work either.
 
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  • #2
I wouldn't "subtract from 270".
The 2.8 is already the angle from south.
According to the left hand rule, it has a component to the left, so it must be 2.8 degrees counterclockwise from south. That would 357.2 degrees clockwise from south.
 
  • #3
It was 182.8 and 357.2. Thanks!
 

FAQ: Direction of electron in magnetic field?

What is the direction of an electron in a magnetic field?

When placed in a magnetic field, an electron will experience a force that is perpendicular to both its motion and the direction of the magnetic field. This force causes the electron to move in a circular path, with the direction of the force always pointing towards the center of the circle.

How does the direction of the magnetic field affect the motion of an electron?

The direction of the magnetic field determines the direction of the force on the electron, which in turn affects the path of the electron's motion. If the magnetic field changes direction, the force on the electron will also change, causing the electron to change its path.

Can an electron change its direction of motion in a magnetic field?

Yes, an electron can change its direction of motion in a magnetic field if the direction of the magnetic field changes or if the electron's speed changes. This is because the force on the electron is always perpendicular to its motion, so any change in the direction of the force will result in a change in the direction of motion.

How does the strength of the magnetic field affect the direction of the electron?

The strength of the magnetic field does not directly affect the direction of the electron, but it does determine the magnitude of the force on the electron. A stronger magnetic field will result in a stronger force on the electron, causing it to move in a tighter circle.

What is the relationship between the velocity of the electron and the direction of the magnetic field?

The velocity of the electron and the direction of the magnetic field are independent of each other. The direction of the magnetic field determines the direction of the force on the electron, while the electron's velocity determines the magnitude of the force. However, the velocity of the electron does affect the path of its motion in the magnetic field.

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