A long vertical wire carries a steady 15 A current. A pair of rails are horizont
ID: 1366987 • Letter: A
Question
A long vertical wire carries a steady 15 A current. A pair of rails are horizontal and are 0.1 m apart. A 7 Ohm resistor connects points a and b, at the end of the rails. A bar is in contact with the rails, and is moved by an external force with a constant velocity of 0.7 m/s as shown. The bar and the rails have negligible resistance. At a given instant t_1, the bar is 0.18 m from the wire, as shown. In Figure, at time t_1, the induced current in mu A is: Express the answer with three decimal places.Explanation / Answer
given,
length of the rod l=0.1 m
speed of the rod v=0.7 m/sec
resistance R=7 ohms
steady curent i=15 A
now,
at a distance d=0.18 m,
magnetic field B=uo*i/2pi*d
and
induced emf on the moving rod E=l*v*B
and
induced current, id=E/R
id=l*v*B/R
id=l*v*uo*i/(2pi*d)*R
id=(0.1*0.7*4pi*10^-7*15)/(2pi*0.18*7)
id=1.6667*10^-7 A
id=0.167 uA