91影视

The rod is determined by two forces: an upward magnetic force and a downward weight force. When the two forces are balanced, the velocity becomes constant.

$F_B=mg$

When a current-carrying wire moves through a magnetism, the field imposes a magnetic pull on the wire. The magnetic force exerted by a wire of length is described by an equation.

$F_B=IlB$

Using Faraday's law to get the magnitude of emf in terms of moving antenna using equation,

$蔚=Blv$

Using Ohm's law to get the Induced current

Use this expression to get the magnetic force,

$F_B=IlB=\left(\frac{Blv}{R}\right)lB=\frac{B^2{l}^{2}v}{R}$

As $F_B=mg$, so we use equation (4) to get the terminal velocity by$mg=\frac{B^2{l}^2{v}_{\text{term}}}{R}$

$v_{\text{term}}=\frac{mgR}{B^2{l}^2}$

$=\frac{\left(10脳{10}^{-3}\mathrm{kg}\right)\left(9.8\mathrm{m}/{\mathrm{s}}^2\right)(0.10惟)}{(0.50\mathrm{T}{)}^2(0.20\mathrm{m}{)}^2}$

$=0.98\mathrm{m}/\mathrm{s}$