Question

An iron rod with a mass m slides on parallel horizontal gold rails, a distance L apart, and carries a current of I. The coefficient of kinetic friction between the rod and rails is μ. What vertical, uniform magnetic field is needed to keep the rod moving at a constant speed? (Enter the magnitude. Use any variable or symbol stated above along with the following as necessary: g

Answer 1

Answer:

The expression is $B=\frac{\mu mg}{IL}$

Explanation:

If the rod is move with constant velocity, the expression of the magnetic field is:

∑Fn = Fm - fk = 0

$BILsin90-\mu n=0\\B=\frac{\mu n}{ILsin90} \\B=\frac{\mu mg}{IL}$

Where

B is the magnetic field

m is the mass

g is the gravity

I is the current

L is the distance

μ is the kinetic friction between the rod and rails