In Figure P20.63, the rolling axle, 1.51 m long, is pushed along horizontal rail

Question

In Figure P20.63, the rolling axle, 1.51 m long, is pushed along horizontal rails at aconstant speed v = 1.00 m/s.A resistor R = 0.401 isconnected to the rails at points a and b,directly opposite each other. (The wheels make good electricalcontact with the rails, so the axle, rails, and R form aclosed-loop circuit. The only significant resistance in the circuitis R.) A uniform magnetic field B = 0.0900 T is directed vertically downwards.

Figure P20.63
(a) Find the induced current I in theresistor.
A
(b) What horizontal force is required to keepthe axle rolling at constant speed?
N
(c)Which end of the resistor, a or b, is at thehigher electric potential?
a
b
(d)After the axle rolls past the resistor, does the current inR reverse direction?
yes
no

Explanation / Answer

GIven lengthof axel L = 1.51 m speed of axel v = 1. 00 m/s magnitude of magnetic field B = 0.09 T emf induced in the axel            = B L v                  = ( 0.09 T ) ( 1.51 m ) ( 1.00 m/s )                = 0.1359 V     a) induced current in the resistor               I =    R               = 0.1359 * 0.401                = 0.0544 A                = 5.44*10^ -2 A    b) horizontal force is required to keepthe axle rolling at constant speed           F = I B   L               = 0.0544 * 0.09 * 1.51                = 7.39*10^ -3 N   c) Here b is at a higher potential than a and the current goesfrom b to a through the resistor d) No, the velocity v of the rolling axle and the magnetic fieldB are unchanged .Thus the polarity is also unchanged.So, the current is directed to b to a in the resistor R. c) Here b is at a higher potential than a and the current goesfrom b to a through the resistor d) No, the velocity v of the rolling axle and the magnetic fieldB are unchanged .Thus the polarity is also unchanged.So, the current is directed to b to a in the resistor R.   

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.