A long vertical wire carries a steady 5 A current. A pair of rails are horizonta
ID: 1347576 • Letter: A
Question
A long vertical wire carries a steady 5 A current. A pair of rails are horizontal and are 0.1 m apart. A 19.5 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 0.4 m/s as shown. The bar and the rails have negligible resistance. At a given instant t1 the bar is 0.15 m from the wire, as shown. In Figure, at time t1, the induced current in mu A is: Express the answer with three decimal places.Explanation / Answer
magnetic field at that instant,
B = miuo*I / (2*pI*d)
= (1.2566*10^-6)*5 / (2*pi*0.15)
=6.67*10^-6 T
induced emf = B*L*V
= (6.67*10^-6)*0.1*0.4
=2.67*10^-7 V
I = induced emf / R
=(2.67*10^-7) / 19.5
= 1.37*10^-8 A
Answer: 1.37*10^-8 A