TPR 5 Right hand rule da eff?

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nkafeel

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This question is from TPR 5, can someone explain to me how the right hand rule works, or how they're showing it?

Fingers (velocity) : point up
Palm (B field) : faces the right
Thumb (force) : into the page

but the image shows, the force is pointing up... kinda confused.


When the current shown in Figure 1 is applied to the pictured galvanometer, in which direction will the needle in Figure 2 be deflected?
  1. uncheckedRadioButton.png
    A.The needle will move clockwise.
    correctAnswer.png

    Correct Answer
    checkedRadioButton.png
    B.
    The needle will move counterclockwise.
    uncheckedRadioButton.png
    C.
    The needle will not be deflected.
    uncheckedRadioButton.png
    D.
    The direction of the movement of the needle cannot be determined.
    Explanation:
    A. The charges moving in the 1 cm sides of the coil experience no initial torque since they are moving either parallel or antiparallel to the magnetic field lines. However, the charges moving in the 2 cm sides will experience forces, in opposite directions, resulting in an initial torque on the coil. Using the equation FB = q(v × B), and invoking the right-hand rule (or the left-hand rule, since the electrons are negatively charged), the directions of the magnetic forces felt by the electrons in the 2 cm sides are shown in the following diagrams:
    Q1050889_1.gif

    Since the left-hand side of the coil experiences an upward force and the right-hand side experiences a downward force, the needle in Figure 2 will rotate clockwise.

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Last edited:
What's wrong with the explanation?
I'd summarize the answer in another way (if you're familiar with magnetic dipole) as follows: i know that the magnetic dipole of the loop is UP by curling my fingers in counterclockwise direction (in direction of current) and pointing my thumb up; thumb represents magnetic dipole moment vector
the dipole moment wants to get parallel with the magnetic field so the loop will rotate clockwise.
 
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