Question

3) The very first magnetic resonance imaging (MRI) devices employed multi-layer copper solenoids, like the one shown in the figure below. The solenoid dimensions were: length = 2 m and inner radius = 0.4 m. The required magnetic field was 0.3 T. Due to thermal considerations, the copper wire conductor was chosen to have a square cross-section, 10 mm×10 mm, which limited the maximum current in the conductor to 1,000 A.

A) What is the minimum number of solenoid layers needed to achieve the required magnetic field? Assume that the conductor in each layer is tightly wound on a cylinder, without any gaps.

B) For the chosen number of layers and using the copper resistivity value at room temperature, estimate the electrical power consumption of this solenoid at 0.3 T.

Answer 1