Magnetic Force on Current

What does the variable 'n' represent in the equation for current in a wire, I = nAv_d q?

• Number of electrons

• Net charge

• Charge carrier density

• Number of atoms

Which of the following equations correctly expresses the net magnetic force on a current-carrying wire in a magnetic field?

• F_B = q(v x B)

• F_B = I(L x B)

• F_B = nAv_d q

• ||F_B|| = ILB sinθ

When is the integral form of the magnetic force equation, F_B = ∫ I(dL x B), typically used for a current-carrying wire?

• When the current is constant

• When the wire is not straight or the magnetic field is not uniform

• When the charge carriers are stationary

• When the wire is very short

In the equation for the magnitude of magnetic force on a straight current-carrying wire, ||F_B|| = ILB sinθ, what does θ represent?

• The angle between the current and the cross-sectional area

• The angle between the direction of the current (or wire length) and the magnetic field

• The angle between the drift velocity and the charge carrier density

• The angle between the magnetic field and the volume of the wire