In Fig. 30-50, a metal rod is forced to move with constant velocity along two pa
ID: 2067186 • Letter: I
Question
In Fig. 30-50, a metal rod is forced to move with constant velocity along two parallel metal rails, connected with a strip of metal at one end. A magnetic field of magnitude B = 0.279 T points out of the page. (a) If the rails are separated by 19.0 cm and the speed of the rod is 46.4 cm/s, what is the magnitude of the emf generated in volts? (b) If the rod has a resistance of 18.8 and the rails and connector have negligible resistance, what is the current in amperes in the rod? (c) At what rate is energy being transferred to thermal energy?
Explanation / Answer
a)
= /t
= BA = B*l*w
= B*l*w/t = B*l*v = (0.279T)(19.0*10^-2m)(46.4*10^-2m/s) = 0.00246 V
b) Ohm's Law: V = IR
I = V/R = (0.00246V)/(18.8) = 1.308*10^-4 A
c) Assuming the rails are frictionless:
P = I*V = (1.308*10^-4A)(0.00246V) = 3.218*10^-7 W