Two ends of the narrow coil are connected to the terminals of an oscilloscope. The solenoid, which was orginally 40cm long is rapidly extended to 140cm long in 50ms. Assume the solenoid is pulled at uniform speed at both ends.. B=3.02*10-3 T magnetic flux density.Narrow coil has a cross sectional area of 2cm by 2cm and 1100 turns.

Calculate the average emf measured by oscilloscope as its extended..
answer is 0.019v

Thanks.