Angle between magnetic field B and velocity of charge

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Homework Help Overview

The discussion revolves around determining the magnitude and direction of the force acting on a charge moving through a magnetic field. The problem involves a charge with a specified velocity and a magnetic field that is oriented out of the page.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to apply the equation for the magnitude of force but expresses confusion regarding the angle between the velocity and the magnetic field. They question whether the angle is 90° based on the magnetic field's orientation.
  • Some participants clarify the direction of the magnetic field and point out that the problem lacks information about the velocity's direction initially, which is later specified as moving from left to right.
  • Another participant suggests a visualization technique to determine the angle between the velocity and the magnetic field direction.

Discussion Status

The discussion is actively exploring the relationships between the vectors involved. Participants are providing clarifications and visual aids to help understand the geometry of the situation, but there is no explicit consensus on the final interpretation of the angle or the resulting force direction.

Contextual Notes

The problem does not define the direction of the velocity initially, which is crucial for solving the problem. The participants are working through the implications of this missing information.

ivanwho49
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Homework Statement



Find magnitude and direction of F of a charge moving through a magnetic field.

velocity: 5 m/s
charge: 2 C
B: 3 T (pointing out of the page when drawn)

Homework Equations



(vector)F=qv x B
(magnitude)F=qvBsinθ


The Attempt at a Solution



I know to use the equation for magnitude but I'm confused as to what the angle would be between v and B. Since the magnetic field is pointing out of the page, would the angle be 90°, making sin(90)=1?

Also, don't know what direction that would be. Since I don't know the direction of B, I'm not sure how to use the right hand rule to figure this out.
 
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You do know the direction of B. It's out of the page.

Unfortunately, the problem does not define the direction of v so you can't solve it.
 
Sorry, forgot to mention that: the velocity moves straight from left to right.
 
ivanwho49 said:
Sorry, forgot to mention that: the velocity moves straight from left to right.

OK, so place a sheet of paper on the table, draw an arrow from left to right = v, then hold a pencil at the back end of the arrow pointing straight up (B).
What is the angle between the arrow and the pencil?
 

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