A very long, straight solenoid with a cross-sectional area of 6.25cm2 is wound w
ID: 1268786 • Letter: A
Question
A very long, straight solenoid with a cross-sectional area of 6.25cm2 is wound with 32 turns of wire per centimeter, and the windings carry a current of 0.235A . A secondary winding of 2 turns encircles the solenoid at its center. When the primary circuit is opened, the magnetic field of the solenoid becomes zero in 5.25
A very long, straight solenoid with a cross-sectional area of 6.25cm2 is wound with 32 turns of wire per centimeter, and the windings carry a current of 0.235A . A secondary winding of 2 turns encircles the solenoid at its center. When the primary circuit is opened, the magnetic field of the solenoid becomes zero in 5.25
Explanation / Answer
A=6.25 cm^2 6.25 x 10^-4 m^2
N/L = 32/cm = 3200/m
I=0.235
B=u0*N*I = 4pix10^-7*3200*0.235 = 9.45 x 10^-4 T
dB/dt= (9.45 x 10^-4 - 0)/5.25 x10^-2 = 0.018
So d(flux)dt = (dB/dt)*A = 1.125 x 10^-5
So Emf in primary= d(flux)/dt = 11.25 x 10^-6 V = 11.25 uV
So EMF in secondary = 2*11.25 uV = 22.5 uV